ELEMENTARY SCIENCE PROGRAM MATH, SCIENCE & TECHNOLOGY EDUCATION A Collection of Learning Experiences NATURES FORCES SIMPLE MACHINES Nature s Forces Simple Machines Student Activity Book Name This learning experience activity book is yours to keep. Please put your name on it now. This activity book should contain your observations of and results from your experiments. When performing experiments, ask your teacher for any additional materials you may need.
TABLE OF CONTENTS Activity Sheet for L.E. #1 - Measuring Mass...2-3 Activity Sheet for L.E. #2 - Measuring Weight...4 Activity Sheet for L.E. #3 - Measuring Force...5-8 Activity Sheet for L.E. #4 - Force, Weight and Mass...9-11 Activity Sheet for L.E. #5 - Gravity Gravity Everywhere...12-17 Activity Sheet for L.E. #6 - Unseen Forces...18-23 Activity Sheet for L.E. #7 - Inclined Plane...24-31 Activity Sheet for L.E. #8 - Wedge...32-33 Activity Sheet for L.E #9 - Screw...34-35 Activity Sheet for L.E. #10 - Levers...36-41 Activity Sheet for L.E. #11 - Pulleys...42-44 Activity Sheet for L.E. #12 - Wheel and Axle...45-46 Natures Forces Simple Machines Student Assessment...47-49 Student Self Assessment...50 Glossary...51-53 1
Activity Sheet for Learning Experience #1 Name MEASURING MASS Mass is a measure of the amount of matter in an object. Mass is defined by physical content, by the number of electrons, protons, molecules, etc. The basic measurement unit for mass is the gram or kilogram. Weight is a measure of the gravitational pull or attractive force of one mass to another mass (generally the Earth). A single ingot of gold would have the same mass wherever it was transported, but the weight of the ingot would be different on Earth than on the Moon or on Mars. The measurement of mass is not affected by gravity. An astronaut may be nearly weightless in space due to low gravity in space but if he were mass-less he would not be there. Calibrate your double pan balance. Mold clay into four ball shapes. Measure the mass of each ball shape with gram centimeter cubes. Add or remove clay to fashion two 25 gram and two 50 gram massed balls. A small amount of talcum powder may be used to reduce stickiness of each clay ball and aid rounding. Compare the masses of the balls by placing them in the double pan balance. Save the clay balls from this learning experience for use in later learning experiences. 2
Activity Sheet for Learning Experience #1 Page 2 1. What does calibrate mean when referring to the double pan balance? 2. Place a 50 gram ball in each basket of the double pan balance. How did your two 50 gram masses compare when you placed one in the basket of each double pan balance? 3. Why do you think the double pan balance acted the way it did when you placed a 50 gram mass in each basket? 4. Place a 25 gram ball in each basket of the double pan balance. How did your two 25 gram masses compare when you placed one in the basket of each double pan balance? 5. Why do you think the double pan balance acted the way it did when you placed a 25 gram mass in each basket? 6. Place two 25 gram balls in one basket and a 50 gram ball in the other basket. How did your two 25 gram masses compare when you placed both in basket of the double pan balance and one 50 gram mass in the other? 7. Why do you think the balance acted the way it did when you placed two 25 gram masses in one basket of the double pan balance and one 50 gram mass in the other pan? 8. The amount of matter is measured in what metric unit? 3
Activity Sheet for Learning Experience #2 Name MEASURING WEIGHT Weight is a measure of the gravitational pull or attractive force of one mass to another mass (generally the Earth). A single ingot of gold would have the same mass wherever it was transported, but the weight of the ingot would be different on Earth than on the Moon or on Mars. For a definition of mass, see activity sheet for Learning Experience #1 in the Natures Forces Simple Machines Student Activity Book. In this learning experience you will use the Newton scale on a spring scale to measure force in Newtons. Find the weight (force) in Newtons on the following objects. Assemble the parts necessary for each measurement. Quantity Object to be measured Weight in Newtons 1 200 gram jar 2 200 gram jar 1 Friction box 1 Double sheave pulley 1 Friction box and double sheave pulley 1 Friction box, double sheave pulley, and friction block 1 Friction block The measure of the gravitational pull on an object is called. The metric unit used to measure weight is called. 4
Activity Sheet for Learning Experience #3 Name MEASURING FORCE A force is a push or pull that changes the motion or shape of an object. A force must be used any time an object begins moving, changes direction, speeds up, slows down, or stops moving. An object that is not being subjected to a force will continue to move at a constant speed and in a straight line. An object that is at rest will remain at rest. This is called inertia. Changes in speed or direction of motion are caused by forces. The greater the force, the greater the change in motion. Think about hitting a ball with a bat. Given the same force, the more massive an object is, the less change in motion will occur. A light ball will go farther than a heavy ball when hit with a bat using the same force. Whenever an object exerts a force on another object, an equal amount of force is exerted back on it. Hitting a light ball with a bat does not hurt your wrists as much as hitting a massive ball. When an object speeds up, slows down, or changes direction, we know that an unbalanced force acted upon it. Force is often called effort in reference to simple machines. The international metric unit of force is the Newton (N). The Newton (N) was named after the English scientist Sir Isaac Newton. Force is commonly measured in pounds in the United States. 1. Place a single 200 gram mass on your desk or table. Pull the 200 gram mass with the spring scale. Record the force necessary to move the 200 gram mass at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 2. Place two 200 gram masses on your desk or table. Pull both 200 gram masses with the spring scale. Record the force necessary to move the 400 gram mass at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 5
Activity Sheet for Learning Experience #3 Page 2 3. Assemble the friction box, friction block, and the double sheave pulley with masonite side down on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 4. Assemble the friction box, friction block, and the double sheave pulley with abrasive side down on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 5. Assemble the friction box, friction block, and the double sheave pulley with double sheave pulley side down on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 6
Activity Sheet for Learning Experience #3 Page 3 6. Assemble the friction box, 200 gram mass jar, and the double sheave pulley with double sheave pulley side down to form wheel on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 7. Assemble the friction box, two 200 gram mass jars, and the double sheave pulley with double sheave pulley side down to form wheel on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on the chart on page 7. 8. Assemble the friction box, friction block, two 200 gram mass jars, and the double sheave pulley with double sheave pulley side down to form wheel on your desk or table. Pull the assembly with the spring scale. Record the force necessary to move the assembly at a steady rate across the surface of the table. Record the force in Newtons on page 7. Object Force in Newtons 1. One 200 gram mass jar 2. Two 200 gram mass jars 3. Friction box, friction block, double sheave pulley with masonite side down 4. Friction box, friction block, double sheave pulley with abrasive side down 5. Friction box, friction block, double sheave pulley with double sheave pulley side down 6. Friction box, 200 gram mass jar, double sheave pulley with double sheave pulley side down 7. Friction box, two 200 gram mass jars, double sheave pulley with double sheave pulley side down 8. Friction box, friction block, two 200 gram mass jars, double sheave pulley with double sheave pulley side down 7
Activity Sheet for Learning Experience #3 Page 4 What force caused the difference in the force in Newtons between objects three and four? What affect did having the wheels make when you compare the data in your table for objects three, four, and five? What must be used anytime an object begins moving? 8
Activity Sheet for Learning Experience #4 Name FORCE, WEIGHT, AND MASS Spring scales are used in this learning experience. The proper way to measure mass is by using a double pan balance. When a double pan balance is used, the effect of gravity is minimized due to the pull of gravity on each arm of the balance. The mass measurement is constant regardless of gravitational force, if we measured an object's mass (amount of matter) with a double pan balance here on Earth and we could measure the object's mass (amount of matter) on the moon it would not change. But, if we measured our weight (force of gravity acting on an object) here on Earth, and then measured our weight on the moon it would be about 1/5 as heavy, because the force of the moon s gravity is about 1/5 that of the Earth s gravity. The moon is about 1/5 as massive as the Earth. Weight in Newtons can be figured out by using an object s mass multiplied by the acceleration of gravity. Weight (Force) = mass x acceleration of gravity (acceleration of gravity near the Earth is 9.8m/s 2 or 32.15 ft/s 2 ). The pound is the unit of force used in the English system of measurement. 9
Activity Sheet for Learning Experience #4 Page 2 The spring scale in this kit has marks on it that will indicate between 0 and 500 grams and between 0 and 5 Newtons. However, mass and force are very different quantities. Mass is a measure of the amount of matter in an object. Force is due to the product of an object's mass and the object's acceleration. Spring scales actually measure forces (F = ma). Spring scales are used to measure the force of an object due to the effect of gravity. The effect of gravity may be shown by hanging one of the 200 gram masses on the hook of the spring. If you look at the Newton side of the scale, it should indicate about 2 Newtons in force. Next hang two of the 200 gram masses on the hook of the spring scale. If you look at the Newton side of the scale, it should indicate about 4 Newtons in force. The spring scale has also been designed to indicate an object's approximate mass. With a spring scale we can only approximate an object's mass. The designers of the spring scale have provided an approximate value for mass by dividing out the effect of the acceleration due to gravity. The force on an object near the surface of the Earth is about 9.8 kg m/s 2. With rounding, we could say that the force of gravity is about 10.0 kg m/s 2. Meter per second squared means that for each second, an object will accelerate and additional 10 meters per second for each second. To eliminate the effect of gravity, the Newton readings on the spring scale have been divided by the approximate acceleration due to gravity of 10.0 kg m/s 2. One Newton equals 1kg/m/s 2 or 1000g/m/s 2. If we approximate the number of grams by dividing the Newton by 10 m/s 2 (the acceleration due to gravity) we find that 100 grams corresponds with the 1 Newton reading on the spring scale. However, the Newton is the proper measure when using the spring scale. Determining mass with a spring scale is only an approximation. 10
Activity Sheet for Learning Experience #4 Page 3 Inspect your spring scale. Use the spring scale to fill in the chart below. Record on the chart below the number of grams that are approximated by dividing the number of Newtons by the acceleration due to gravity of about 10 m/s 2. 1N= 1Kg x 1 m/s2 or 1N=1000g x 1m/s2. Newton of Force Divided by the acceleration due to gravity of approximately 10.0 m/s 2 1 10.0 m/s 2 Approximately Number of Grams Mass 2 10.0 m/s 2 3 10.0 m/s 2 4 10.0 m/s 2 5 10.0 m/s 2 Mass is a measure of the amount of matter in an object. Use your double pan balance, gram centimeter cubes, 25 and 50 gram balls or 200 gram jars and the spring scale to measure the masses of the objects listed below. Objects Double Pulley Friction Box Friction Block Mass with double pan balance Approximate Mass with spring scale Which method used above do you believe is the most accurate method to measure an object s mass? Why do you think that the method that you selected is the most accurate method? 11
Activity Sheet for Learning Experience #5 Name GRAVITY - GRAVITY EVERYWHERE Acceleration Due to Gravity Near the surface of the Earth, the force of gravity causes falling objects to accelerate at 9.8 meters per second squared (9.8m/s 2 ). Therefore, the downward velocity of the falling object increases 9.8 meters per second for each second that the object falls. The Change in Velocity and Distance Traveled due to the Acceleration of Gravity chart below illustrates the effect of gravity on all objects near the Earth's surface. Changes in Velocity and Distance due to Acceleration by Gravity (Metric) Time in Seconds Velocity Downward (m/s) Velocity Downward (km/hr) Distance Traveled 0 0.0 m/s 0.0 km/hr 0.0 m 0.05.49m/s 1.76 km/hr 24.5 cm /.245m 0.1.98m/s 3.53 km/hr 49 cm /.49m 0.2 1.96m/s 7.06 km/hr 98 cm /.98m 0.4 3.92m/s 14.12km/hr 196cm/1.98m 0.5 4.9m/s 17.64 km/hr 245 cm /2.45m 1 9.8 m/s 35.3 km/hr 4.9 m 2 19.6 m/s 70.6 km/hr 19.6 m 3 29.4 m/s 105.9 km/hr 44.1 m 4 39.2 m/s 141.2 km/hr 78.4 m 5 49.0 m/s 176.5 km/hr 122.5 m The acceleration of an object while falling is the same for any object regardless of the object's mass, provided the air resistance is the same. The velocity of the object at impact will be the same. The only difference is the amount of momentum at impact. When a 1 kg ball and a 100 kg ball are dropped from a tall building, the acceleration is the same for each ball, 9.8m/s 2. This means they will hit the ground at the same time. The force attracting the 100 kg ball is 100 times greater than the force attracting the 1 kg ball due only to the difference in mass. The momentum of the 100 kg ball is much greater than the momentum of the 1kg ball. The impact of the object's momentum is called impulse. The 100 kg ball will have a much greater impulse when it hits the surface than the 1 kg ball. 12
Activity Sheet for Learning Experience #5 Page 2 Friction Friction is a force that opposes motion. All moving objects have friction between them when they touch including objects moving though water or air. Rough surfaces have more friction when they rub against other objects than smooth surfaces do. Regardless of how it may feel, no surface is perfectly smooth. When two surfaces rub together the roughness (tiny bumps, craters, and splinterlike projections) catch on the roughness of the other surface resulting in friction. Liquid materials such as oils or waxes are often used between surfaces to reduce friction. Friction between objects in air or water is often called drag. Inertia Inertia is the tendency of an object to remain at rest, if it is at rest. It is also the tendency to continue moving in the direction it is traveling, if it is moving. An object's inertia is determined by its mass. Momentum Momentum is a property possessed by moving objects that is the product of an object's mass, velocity, and direction or mass x velocity. Momentum = mass x velocity Your task is to assemble and calibrate a double pan balance. You may use the 25 and 50 gram balls that were used in the previous learning experience. Remeasure or measure the pieces of clay into one 25 gram and one 50 gram ball. Each piece of clay should be rolled into a very round ball. A small amount of talcum powder may be used to reduce stickiness of each clay ball and aid rounding. The balls of clay will be dropped from various heights and the diameter of the impact mark on the clay ball recorded. Two measurements of the diameter of the impact should be taken at 90 degrees to each other and the average calculated. The ball will need to be re-rounded after each trial. 13
Activity Sheet for Learning Experience #5 Page 3 Each ball will need to be dropped from the following heights- 25 cm, 50 cm, 75 cm, 100 cm and 200 cm. Record the diameter of the impact mark on each ball as shown in the diagram below. Velocity at impact may be found on the chart on the previous page. Data Table for the 25 gram Mass Ball Height Diameter of Impact Diameter of Impact at 90 degrees Average Diameter of the Impact Approximate Velocity at Impact km/hr downward 25 cm 50 cm 75 cm 100 cm 200 cm 1. If you fell from a height of about 1 meter, what would be your velocity at the time you impacted the ground? 2. If you fell from a height of about 2 meters, what would be your velocity at the time you impacted the ground? 3. If you fell from a height of about 2.5 meters, what would be your velocity at the time you impacted the ground? 14
Activity Sheet for Learning Experience #5 Page 4 4. If you fell from a height of about 20 meters, what would be your velocity at the time you impacted the ground? 5. If you fell from a height of about 45 meters, what would be your velocity at the time you impacted the ground? Data Table for the 50 gram Mass Ball Height Diameter of Impact Diameter of Impact at 90 degrees Average Diameter of the Impact Approximate Velocity at Impact km/hr downward 25 cm 50 cm 75 cm 100 cm 200 cm 1. What did your data show for the 25 gram ball? 2. What did your data show for the 50 gram ball? 3. Is there any friction acting on either ball at any time? 4. What other forces might be acting on the ball? 5. Which ball had the greatest momentum? 15
Activity Sheet for Learning Experience #5 Page 5 6. What might happen to a clay ball if its mass was increased but dropped from the same height as a smaller ball? 7. How might a change in mass affect an object s momentum? Look at the (Changes in Velocity and Distance due to Acceleration by Gravity) (Metric) table. 1. Find the velocity for an object that has traveled for about 50 cm and write its velocity here. 2. Find the velocity for an object that has traveled for about 1 m and write its velocity here. 3. Find the velocity for an object that has traveled for about 2 m and write its velocity here. Momentum Momentum is a property possessed by moving objects that is the product of an object's mass, speed, and direction or mass x velocity. Use a calculator to find the following: 1. Find the momentum of the 25 gram ball after falling for about 50 cm and write the answer here. 2. Find the momentum of the 50 gram ball after falling for about 50 cm and write the answer here. 3. Find the momentum of the 25 gram ball after falling for about 1 m and write the answer here. 4. Find the momentum of the 50 gram ball after falling for about 1 m and write the answer here. 5. Find the momentum of the 25 gram ball after falling for about 2 m and write the answer here. 6. Find the momentum of the 50 gram ball after falling for about 2 m and write the answer here. 16
Activity Sheet for Learning Experience #5 Page 6 7. What relationship do you find in the momentum of the 25 gram ball compared to the 50 gram ball. 8. This table has been included to allow some comparisons with the student s understandings of speed related to vehicles and the acceleration due to gravity. Changes in Velocity and Distance due to Acceleration by Gravity Time in Seconds Velocity Downward (ft/s) Velocity Downward (mi/hr) Distance Traveled 0 0.0 ft/s 0.0 mi/hr 0.0 mi 0.05 1.61 ft/s 1.10 mi/hr 9.7 in /.81 ft 0.1 3.22 ft/s 2.19 mi/hr 19.32 in / 1.61 ft 0.2 6.43 ft/s 4.38 mi/hr 38.6 in / 3.22 ft 0.4 12.88ft/s 8.76mi/hr 77.28 in /6.44 ft 0.5 16.08 ft/s 10.96 mi/hr 96.48 in / 8.04 ft 1 32.15 ft/s 21.92 mi/hr 16.1 ft. 2 64.3 ft/s 43.8 mi/hr 64.3 ft 3 96.45 ft/s 65.76 mi/hr 96.45 ft 4 128.6 ft/s 87.68 mi/hr 128.6 ft 5 160.75 ft/s 109.6 mi/hr 160.75 ft 17
Activity Sheet for Learning Experience #6 Name UNSEEN FORCES Session 1 Place 30 gram centimeter cubes in the bottom of a 9 oz. plastic tumbler. Place an index card on top of the tumbler with a penny placed in the center of the card. A quick flick of a finger should move the card forward. Observe what happens to the penny. Repeat the procedure several times. What did you observe? What is your explanation for what you observed about the movement of the index card and the penny? Repeat the procedure while using one, two, three, and four pennies. What did you observe? What is your explanation for what you observed about the movement of the index card and the pennies? 18
Activity Sheet for Learning Experience #6 Page 2 Place 30 gram centimeter cubes in the bottom of a 9oz. plastic tumbler. Place a piece of index card sized abrasive paper on top of the tumbler with a penny placed in the center of the abrasive paper. Abrasive side should be up. A quick flick of a finger should move the abrasive paper forward. Observe what happens to the penny. Repeat the procedure several times. What did you observe? What is your explanation for what you observed about the movement of the abrasive paper and the penny? Repeat the procedure while using one, two, three, and four pennies. What did you observe? What is your explanation for what you observed about the movement of the abrasive paper and the pennies? 19
Activity Sheet for Learning Experience #6 Page 3 Session 2 Select a 3 x 5 index card. Measure and draw the first rectangle (30 x 60 mm) illustrated on pages 21-22. Measure and draw a line in the center of the rectangle 30 mm from the edge of the rectangle to make 2 squares 30 x 30 mm. Measure and draw a line parallel to the long side of the rectangle, 10 mm from the edge. Measure and draw a line to form two rectangles that are 10 mm x 10 mm next to the centerline of the rectangle and next to the edge of the long side of the rectangle. Cut the rectangle out of the index card. Cut slots on three lines as illustrated on page 23. Each cut will be 10 mm in length. Fold the cut card on the lines that you have drawn and attach to a flexible ruler with a small butterfly clip as illustrated on page 23. Place one penny on each side as illustrated and launch the pennies by bending the flexible ruler. Listen for the sound of the impact of each penny. What is your conclusion for the affect of gravity on each penny? What forces acted on the pennies as they were launched? 20
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Activity Sheet for Learning Experience #6 Page 6 Released Bend here and release with two pennies. 23
Activity Sheet for Learning Experience #7 Name INCLINED PLANE Incline plane 200 gram mass Spring scale Pole 2 200 gram masses Friction box Double sheave pulley Offset base Diagram 1 Diagram 2 24
Activity Sheet for Learning Experience #7 Page 2 Session 1 Use a protractor to draw an angle line on a 5 x 8 index card. See pages 27, 29, and 30. Set the ramp at 10, 20, and 30 degrees as required by the tables below. Apply force to the Newton Spring scale to move the objects up the incline plane required by the tables. Record the force in Newton required to move the object at a constant rate. Ramp angle 10 degrees. Friction box, friction block, double sheave pulley with masonite side down Friction box, friction block, double sheave pulley with abrasive side down Friction box, friction block, double sheave pulley with double sheave pulley side down Friction box, 200 gram mass jar, double sheave pulley with double sheave pulley side down (see diagram 1 on previous page) Friction box, two 200 gram mass jars, double sheave pulley with double sheave pulley side down (see diagram 2 on previous page) Friction box, friction block, two 200 gram mass jars, double sheave pulley with double sheave pulley side down Newton Force What forces do you think were acting on the objects as they were being pulled up the ramp? What is your explanation for differences in the amount of force needed to move the objects up the ramp? Ramp angle 20 degrees. Friction box, friction block, double sheave pulley with masonite side down Friction box, friction block, double sheave pulley with abrasive side down Friction box, friction block, double sheave pulley with double sheave pulley side down Friction box, 200 gram mass jar, double sheave pulley with double sheave pulley side down (see diagram 1 on previous page) Friction box, two 200 gram mass jars, double sheave pulley with double sheave pulley side down (see diagram 2 on previous page) Friction box, friction block, two 200 gram mass jars, double sheave pulley with double sheave pulley side down Newton Force 25
Activity Sheet for Learning Experience #7 Page 3 What forces do you think were acting on the objects as they were being pulled up the ramp? What is your explanation for differences in the amount of force needed to move the objects up the ramp? Ramp angle 30 degrees. Friction box, friction block, double sheave pulley with masonite side down Friction box, friction block, double sheave pulley with abrasive side down Friction box, friction block, double sheave pulley with double sheave pulley side down Friction box, 200 gram mass jar, double sheave pulley with double sheave pulley side down (see diagram on page 24) Friction box, two 200 gram mass jars, double sheave pulley with double sheave pulley side down (see diagram 2 on page 24) Friction box, friction block, two 200 gram mass jars, double sheave pulley with double sheave pulley side down Newton Force What forces do you think were acting on the objects as they were being pulled up the ramp? What is your explanation for differences in the amount of force needed to move the objects up the ramp? 26
Activity Sheet for Learning Experience #7 Page 4 Session 2 Set up and calibrate the double pan balance as previously done in Learning Experience #4. Place 50 gram centimeter cubes in one plastic jar. Place the jar with 50 gram centimeter cubes in one basket of the balance and an empty jar in the other basket. Pour water into the empty jar until the double pan balance is balanced. Remove the jar of water from the basket. Place an empty jar in the basket. Place rice in a jar until the mass is 50 grams. The same procedure should be done with an additional jar with salt. You should now have four jars that have a mass of 50 gram. Use the index card created for Learning Experience #7, Session 1. Set the height of the ramp at 10 degrees. Be prepared to catch the jar after the jar has rolled down the ramp. Make sure the ingredients in the jar are leveled out on the long side of the jar. Place the jar with 50 grams of centimeter cubes on the ramp at the 15 cm mark. Release the jar. 27
Activity Sheet for Learning Experience #7 Page 5 1. What did you observe related to the movement of the jar with 50 grams of centimeter cubes? 2. What is your explanation for the action of the jar? Select the jar with water. Place the jar with 50 grams of water on the ramp at the 15 cm mark. Release the jar. 3. What is your explanation for the action of the jar? Select the jar with rice. Place the jar with 50 grams of rice on the ramp at the 15 cm mark. Release the jar. 4. What is your explanation for the action of the jar? Select the jar with salt. Place the jar with 50 grams of salt on the ramp at the 15 cm mark. Release the jar. 5. What is your explanation for the action of the jar? Tap the jars on the table to pack the ingredients at the bottom of the jar. Set the ramp at 10 degrees. Predict what you think will happen when you repeat previous trials. 6. What will the jar with the centimeter cubes do? 7. What will the jar with the water do? 8. What will the jar with the rice do? 9. What will the jar with the salt do? Place each jar at 15 cm up the ramp one at a time and record your observation. 10. What did you observe? 11. What is your explanation for the action of the jars? 28
Activity Sheet for Learning Experience #7 Page 6 Set the ramp at 20 degrees. Repeat the trials from Session 2. In the first trials, use the jars with the ingredients leveled out on the long side of the jar. On the second trials, use the jars with the ingredients packed at the bottom of the jar by tapping the jar bottom on the table. 12. What did you observe related to the movement of the jar with 50 grams of centimeter cubes? 13. What is your explanation for the action of the jar? Select the jar with water. Place the jar with 50 grams of water on the ramp at the 15 cm mark. Release the jar. 14. What is your explanation for the action of the jar? Select the jar with rice. Place the jar with 50 grams of rice on the ramp at the 15 cm mark. Release the jar. 15. What is your explanation for the action of the jar? Select the jar with salt. Place the jar with 50 grams of salt on the ramp at the 15 cm mark. Release the jar. 16. What is your explanation for the action of the jar? 29
Activity Sheet for Learning Experience #7 Page 7 Tap the jars on the table to pack the ingredients at the bottom of the jar. Set the ramp at 20 degrees. Predict what you think will happen when you repeat previous trials. 17. What will the jar with the centimeter cubes do? 18. What will the jar with the water do? 19. What will the jar with the rice do? 20. What will the jar with the salt do? Place each jar at 15 cm up the ramp one at a time and record your observation. 21. What is your explanation for the action of the jars? Session 3 Set the ramp at 30 degrees. Place a #82 rubberband on each end of the plastic jars. Release each jar down the ramp. Repeat the trials from Session 2. In the first trials, use the jars with the ingredients leveled out on the long side of the jar. On the second trials, use the jars with the ingredients packed at the bottom of the jar by tapping the jar bottom on the table. 22. What did you observe related to the movement of the jar with 50 grams of centimeter cubes? 23. What is your explanation for the action of the jar? 30
Activity Sheet for Learning Experience #7 Page 8 Select the jar with water. Place the jar with 50 grams of water on the ramp at the 15 cm mark. Release the jar. 24. What is your explanation for the action of the jar? Select the jar with rice. Place the jar with 50 grams of rice on the ramp at the 15 cm mark. Release the jar. 25. What is your explanation for the action of the jar? Select the jar with salt. Place the jar with 50 grams of salt on the ramp at the 15 cm mark. Release the jar. 26. What is your explanation for the action of the jar? Tap the jars on the table to pack the ingredients at the bottom of the jar. Set the ramp at 30 degrees. Predict what you think will happen when you repeat previous trials. 27. What will the jar with the centimeter cubes do? 28. What will the jar with the water do? 29. What will the jar with the rice do? 30. What will the jar with the salt do? Place each jar at 15 cm up the ramp one at a time and record your observation. 31. What is your explanation for the action of the jars? 31
Activity Sheet for Learning Experience #8 Name WEDGE A wedge is a simple machine that is used to spread an object apart or to raise an object. A wedge has a sloping surface like an inclined plane. It is made with two inclined planes placed back to back. A wedge multiplies a force. This force may be used to penetrate very hard objects. Any effort that is applied to the wide end of the wedge is concentrated on the narrow edge making actions like splitting logs or cutting with a knife easier. The tip of a needle, a chisel, the blade on a plow, a knife, an axe, and a paper cutter are all examples of wedges. By decreasing the thickness of the cutting edge, less effort is needed to move through the object being cut. The tip of a wood screw is a wedge and the edge of the thread is also a wedge. Cutting tools generally contain a wedge. In the space below, make drawings of three simple machines that use a wedge. 32
Activity Sheet for Learning Experience #8 Page 2 Set the pole clamp at a height of 8 cm to the center of the pole rod. Place the handle on the rod. Place the sharpest wedge on the handle. Roll a piece of clay into a cylinder about 2 cm in diameter and about 10 cm long. Align the handle and wedge in line with the clay cylinder. Lift the handle to vertical and let go of the handle. The wedge will mark the clay. Change wedges and repeat process. A B C Which wedge shape made a deeper mark on the clay cylinder? What is your explanation for why one wedge made a deeper mark on the clay than the other wedge? 33
Activity Sheet for Learning Experience #9 Name SCREW A screw is a simple machine in the form of an inclined plane wrapped around a central shaft. The grooves on a screw are called threads. The wrapped thread is the inclined plane. The distance between the threads is called the pitch. The smaller the pitch, the less force it takes to twist the screw but the distance the screw must be turned is increased. A screw is one of the strongest means of binding two things together. Screws may be found in light bulbs, bolts, wood screws, drill bits, c-clamps, and twist off caps from bottles. A spiral staircase is a large version of a screw. Fine Coarse Inspect the large bolts and nuts provided in the kit. They have a different number of threads and therefore a different pitch. One has fine thread. One has coarse. Cut five strips of copy paper 2 cm wide. Join two strips with tape end to end. Join the three other strips end to end. The distance around the bolts is 6 cm. The number of times the thread wraps around the coarse bolt is eight times. Mark off 8-6 cm distances of the shorter strip of paper. Draw a diagonal line on the paper strip. Cut on the diagonal line as done in session 1. You will now make a second model using the three paper strips that you have taped together. Repeat the process used for the course bolt and the fine thread bolt. The number of times the thread wraps around the fine threaded bolt is thirteen times. Mark off 13-6 cm distances on the long strip of paper. Draw the diagonal line and cut on the diagonal line. Compare a strip from the first sample (coarse thread) with the second (fine thread). 34
Activity Sheet for Learning Experience #9 Page 2 You have created two different inclined planes, one from the coarse thread bolt and one from the fine thread bolt. Based on the inclined planes that represent the threads, how would you explain the advantages that each bolt has? Advantages of the fine threaded bolt- Advantages of the coarse threaded bolt- 35
Activity Sheet for Learning Experience #10 Name LEVERS A lever is a bar or rod that is free to move on a fulcrum. A fulcrum is the turning point for any lever. The distance from where the force is applied to the fulcrum is called the effort arm. In the example of a simple lever machine (a pry bar) below, the effort from a hand is applied to the effort arm. The lever s shorter distance from the edge of the paint can to the lid is the resistance arm. A closed can of paint is usually difficult to open. With a pry bar, the lid may be easily removed. The pry bar or lever changes the size and direction of the force needed to remove the lid. Scissors, tin snips, nutcrackers, tongs, a broom, a mop, a baseball bat, and fishing rods are all examples of common levers. Simple levers have one great disadvantage in that the resistance can t be moved very far. In a first class lever, the fulcrum is located between the force (effort) and the resistance. Example: sea-saw. First Class Lever 36
Activity Sheet for Learning Experience #10 Page 2 In a second class lever, the resistance (load) is located between the force (effort) and the fulcrum. Example: wheelbarrow or a nutcracker. Second Class Lever In a third class lever, the force (effort) is located between the fulcrum and the resistance (load). Example: sweeping broom or ice tongs. Third Class Lever 37
Activity Sheet for Learning Experience #10 Page 3 Arrange the flat lever and fulcrum as shown in the image below. The fulcrum should be positioned in the middle of the lever about 12 cm from each end. Calibrate the lever as close as you can to balance using some clay. Place 50 gram centimeter cubes in one jar with its top on and place the jar at the end of the lever. Place another jar on the other end of the lever. Add rice to the empty jar until the lever just balances or as close as you can to balance. Be sure to include both tops to the jars. You now have a first class lever working as a balance. The mechanical advantage (MA) of the lever is 1. Repeat the previous procedure and create two additional jars, each with 50 grams of mass. One jar should have salt and one should have water. 38
Activity Sheet for Learning Experience #10 Page 4 Position the jar of rice at one end of the lever with the fulcrum in the middle. Place the jar with the gram cubes and the jar with the salt at a location on the other end of the lever about halfway between the end and the fulcrum. Move the two jars until the system balances or as near as you can. You now have a first class lever with a mechanical advantage of 2. The 50 gram jar of rice should cause the combined 100 gram mass of the jar of salt and 50 gram cubes to be easily balanced or moved. 39
Activity Sheet for Learning Experience #10 Page 5 Position the jar of rice at one end of the lever with the fulcrum in the middle. Place the jar with the gram cubes, the jar with the salt, and the jar of water as shown at a location on the other end of the lever about one-third of the way between the end and the fulcrum. Move the three jars until the system balances or as near as you can. You now have a first class lever with a mechanical advantage of 3. The 50 gram jar of rice should cause the combined 150 gram mass of the jar of salt, 50 gram cubes and 50 grams of water to be easily moved. 1. For a lever with a mechanical advantage of 1, did the distance of the effort (gram cubes) moved differ from the distance that the resistance (jar of rice) moved up or down? 2. For a lever with a mechanical advantage of 2, how did the distance of the effort (jar of rice) moved differ from the distance that the resistance (jar of salt and jar of gram cubes) moved up or down? 3. For a lever with a mechanical advantage of 3, how did the distance of the effort (jar of rice) moved differ from the distance that the resistance (jar of salt, jar of gram cubes and jar of water) moved up or down? 4. If you had a heavy load to move, how would you arrange the lever? On the drawing below show where you would position the fulcrum to lift the heavy rock. Draw the fulcrum where you think it should be positioned. 40
Activity Sheet for Learning Experience #10 Page 6 Identify the class of lever shown in the drawings above. Write first, second, or third class lever in the spaces below. 1. 2. 3. 4. 5. 6. 41
Activity Sheet for Learning Experience #11 Name PULLEYS A pulley is another kind of simple machine. It is simply a wheel with a rope, belt or chain around it. It is used to change the direction of movement or the amount of force. Fixed pulleys only change the direction that something moves. Moveable pulleys move with the resistance forces (load) and are able to multiply the effort force we put in. Because the pulley moves too, it is able to multiply our effort and increase force. What you gain in force you loose in the distance you pull the rope. A block and tackle is a combination of fixed and moveable pulleys. It changes the direction of movement and also multiplies the effect of the effort. That is why it s used to lift heavy loads. Pulleys are used in most cranes, elevators, and exercise equipment. Your task is to collect data on the operation of a variety of pulley arrangements. Each arrangement will require a triple sheave pulley at the top. Attach the triple sheave pulley to the pole clamp with a s-hook. You will want to place the offset base away from the pole clamp. Place a textbook on the offset base. A 200 gram mass will be used for each arrangement. A ribbon is provided. Attach the ribbon to the frame of the pulley with the velcro end. A small butterfly clip may be attached to the ribbon to shorten the ribbon. The 200 gram mass should be attached to the double sheave pulley with an S-hook. The Newton scale should be attached to pull in the direction indicated by the arrow in each drawing. Determine the weight in Newtons of the 200 gram mass plus the double sheave pulley. Follow the drawings A-F. Record your data in the table on the page 43. 42
Activity Sheet for Learning Experience #11 Page 2 A B C D E F 43
Activity Sheet for Learning Experience #11 Page 3 1. Which arrangement of pulleys of ribbon require the least amount of force to lift the 200 gram mass and double pulley? 2. Which arrangement of pulleys of ribbon require the greatest amount of force to lift the 200 gram mass and double pulley? Set up the arrangement as shown in drawing F. Attach a 200 gram mass to the double pulley and a 200 gram mass to the ribbon when the Newton scale was attached. Each weight should be free to move. 3. Describe what you observed. 4. What is your explanation? 5. In which arrangement A-F, did the effort on the ribbon lift the 200 gram mass have to travel the greatest distance to cause movement of the 200 gram mass? Pulley Arrangement A B C D E F Force in Newtons 6. For a pulley system to be able to move a heavy weight, how would you arrange the pulleys and ribbons? 7. Which pulley system A-F had the greatest mechanical advantage? 8. Which pulley system A-F had the least mechanical advantage? 44
Activity Sheet for Learning Experience #12 Name WHEEL AND AXLE A wheel and axle machine results when a spinning lever rotates around a center fulcrum. The wheel is a continuous lever. The wheel is always rigidly attached to the axle. The wheel and axle is often confused with the wheels on vehicles, which is a pair of wheels and axles. In the wheel and axle machine, an effort is applied to the wheel. An attached axle turns as a result. The effort at the wheel is multiplied at the axle. The force applied at a doorknob turns around the fulcrum at the axle. The effort is multiplied at the resistance, which is the bolt and the lock. A screwdriver can also be a wheel and axle machine. The handle is the wheel and the metal shaft is the axle. The head of the screw is a wheel and the shaft is an axle. Examine the mechanical pencil sharpener in your classroom. The crank handle is attached to an axle that turns a wheel geared to roller blades that sharpen the pencil. The larger the handle or wheel, the easier it is to turn the axle. 45
Activity Sheet for Learning Experience #12 Page 2 Wheel Wheel Axle Axle Cut a strip of copy paper 1 x 25 cm long. Wrap the strip of paper around the shaft of the large bolt and cut the paper to that distance. Wrap a strip around the head of the bolt and cut the paper to that distance. 1. How long was the paper strip from the shaft of the bolt? mm. 2. How long was the paper strip from the head of the bolt? mm. 3. Which distance is longer, the distance around the head of the bolt or the distance around shaft of the bolt? Repeat the procedure in step #1 for a doorknob. Use you pencil for the size of the shaft for the doorknob. 4. How long was the paper from the pencil (doorknob shaft)? mm. 5. How long was the paper from the doorknob? mm. 6. Which distance is longer? 7. If you had to turn a shaft (axle) that was attached to a heavy load, would you want a large or a small wheel for turning? Explain why 8. The distance the knob and the distance the doorknob shaft turned is related to the mechanical advantage of the wheel and axle machine. Compare the two distances (lengths of paper). What is the approximate mechanical advantage of the doorknob and shaft that you compared? 46
Name: Date: Natures Forces Simple Machines Student Assessment Directions: Read the question carefully and answer based on your knowledge about natures forces simple machines. Place the correct number in the space provided. 1. What is the force of attraction between any 2 objects? 1. Friction 2. Inertia 3. Gravity 4. Motion 2. An object that is sitting there (at rest) stays there. This is called 1. Friction 2. Inertia 3. Gravity 4. Motion 3. Which inclined plane would need more force to pull an object up? 1. 2. 3. 4. 4. A doorknob is what kind of simple machine? 1. lever 2. pulley 3. wedge 4. wheel & axle 5. Which of the following simple machines is a lever? 1. wheel barrow 2. Scissors 3. Hammer 4. All of these 6. Look at the picture of the see saw below. It is a first class lever. What is the part called that the arrow is pointing to? 1. The resistance 2. The effort 3. The fulcrum 7. What unit do we measure metric mass in? 1. meter 2. liter 3. degree 4. gram 8. If you were to go into space, which of the following would not change? 1. mass 2. weight 3. gravity 4. friction 9. When you stand on the scales, what force affects your weight? 1. Friction 2. Inertia 3. Gravity 4. Motion 47
Natures Forces Simple Machines Assessment Page 2 10. If you push on a wall and you and the wall isn t moving, which statement is true? 1. The wall is pushing with more force than you 2. The wall is pushing with less force than you 3. The wall is pushing with the same force as you 4. The wall doesn t push at all 11-12. Here is a drawing of 2 objects. The more mass the object has, the greater the attraction of gravity. 10 g 100 g 11. Which object would weigh the most? Explain your answer using the word gravity. 12. If there is less gravity would you need more or less force to lift it? Explain your answer. Use the following drawings to answer the next 2 questions. The drawings represent a box sitting on a table. 10 kilograms 20 kilograms 30 kilograms 13. Which of the boxes would have the greatest friction? Explain your answer. 14. What would happen to the friction if you put wheels on the boxes? Use the following drawings for the next 2 questions. The following experiment has the same inclined plane, a ball going down it and a box at the bottom that the ball hits and moves. 5 kg 10 kg # 1 # 2 48
Natures Forces Simple Machines Assessment Page 3 15. Which ball will move the box farthest? Why? 16. Which ball will have the most momentum? Why? 17. You have learned about Gravity and Friction. Think about riding your bicycle. Write a sentence that tells how gravity and friction help make your bike work? 18. Which would have momentum, a school bus or a car if both are going the same speed? Explain your answer! 19. This is a hard question... think about it! If there were no wind pushing up, which object would fall the fastest if dropped... A penny or a brick? Explain your answer. 20. You are going to do an experiment to see if friction is greater when you rub a block with sand paper or with a crayon. What would be your educated guess (hypothesis) about the answer? What are two steps you could take to find the answer? 49
NATURE'S FORCES SIMPLE MACHINES STUDENT SELF-ASSESSMENT Name: Date: 1. What do you now know about the ways that screws and inclined planes are similar that you didn t know before? 2. What do you know about the how pulleys can be arranged that make it easier to move heavy objects? 3. What are some differences between weight (force) and mass? 4. How well do you think you and your partner(s) worked together? Give some examples. 5. What learning experiences did you enjoy? Explain why did you liked them. 6. Were there any learning experiences in the unit you didn t understand or that confused you? Explain your answer. 7. Take another look at your activity sheets and science notebook. Describe how well you think you recorded your observations and ideas. 50
GLOSSARY Acceleration Action Axle Block and Tackle Compound Machine Distance Efficiency Effort Arm Energy Equal Fixed Pulley Force Friction Fulcrum Gravity Inclined Plane Increase any increase in the speed an external force (the action) that is applied to a body and that is counteracted by an equal force in the opposite direction (the reaction). a rod or shaft on which a wheel turns. a combination of fixed and movable pulleys used together. a machine made up of two or more simple machines. the space between two objects or a measure of a change in position. the amount of work done by a machine compared to the amount of work put into it. on a lever, the distance from the force to the fulcrum. the ability to do work. of the same quality, value, degree, or intensity. a pulley that stays in place as the load moves. a push or a pull. a force that slows the motion of two objects rubbing against each other. the turning point of lever. the natural attraction that tends to draw bodies together. Ex. Bodies are drawn toward the center of the earth. a slanted surface that connects one level to a higher level. A simple machine. to become greater in amount, size, degree. 51
Inertia Lever Load Machine Magnetism Mass Mechanical Advantage Movable Pulley Multiple Pitch Position Predict Pulley Reaction Reduce Resistance Resistance Arm the property of a material body, due to its mass, by which it resists any change in its motion unless it is overcome by force. Thus if no outside forces are present, a stationary body will remain at rest and a moving body will continue to move in the same direction at the same speed. a bar or rod resting on a turning point or fulcrum A simple machine. object to be moved or lifted by a lever. anything that makes work easier. the properties of attraction possessed by magnets. the amount of matter in an object the work produced by the machine, divided by the force applied to it. a pulley that moves with the load. having or consisting of many parts. the distance between two threads in a screw. the location of an object. what one believes will happen. (fixed, movable) a wheel with a rope moving around it. A simple machine. an external force (the action) that is applied to a body and that is counteracted by an equal force in the opposite direction (the reaction). to lessen in any way, as in size, weight, amount, value. the opposition of a thing to movement by a force. the distance from the fulcrum to the point where the resistance is exerted or lifted (load arm). 52