GPE = m g h. GPE = w h. k = f d. PE elastic = ½ k d 2. Work = Force x distance. KE = ½ m v 2

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1 1 NAME PERIOD PHYSICS GUIDESHEET ENERGY CONVERSIONS POTENTIAL AND KINETIC ENERGY ACTIVITY LESSON DESCRIPTION SCORE/POINTS 1. NT CLASS OVERHEAD NOTES (5 pts/page) (Plus 5 pts/page for sample questions) /20 3 foldables 30 pts each /30 2. TX PP READING GUIDE /31 3. TX PP READING GUIDE /39 4. WS REVIEW QUESTIONS/MATH WS /83 Gravitational Potential Energy = Weight Height = Mass Gravity Height GPE = w h GPE = m g h Weight = Mass gravity Gravity 9.8 m/sec 2 Elastic Potential Energy = ½ spring constant distance 2 PE elastic = ½ k d 2 Linear Kinetic Energy = ½ mass Velocity 2 KE = ½ m v 2 spring constant = force distance k = f d Work = Force x distance Work = F x D

2 2 GRAVITATIONAL POTENTIAL ENERGY NOTES Energy that is stored by lifting it to a higher position. The formula to find GPE is Write 5 sample test questions next to your notes on this side You lift a 50 pound box to a shelf that is 5 feet high. How much work did you do to lift it? How much potential energy is stored in the box? **This shows that the work done to lift the box is stored in the box as potential energy. A 2 kg box is on a shelf 3 meters high. How much potential energy does it have? (gravity = 9.8 m/sec) A 8 kg rock balances on a ledge 50 meters high. Find the gravitational potential energy. (gravity = 9.8 m/sec) LINEAR KINETIC ENERGY NOTES The formula to find kinetic energy is: A hammer with a mass of 2 kg is moving 4 meters/sec. How much kinetic energy does it have? If you double the mass to 4 kg, and it still moves 4 m/s, How much kinetic energy? What if you double the speed from 4 meters/sec to 8 meters/sec. The mass is still 2 kg. What is the kinetic energy?

3 3 A person and bicycle together have a mass of 600 kg. If they are traveling at 8 meters/sec, how much kinetic energy do they have? Write 5 sample test questions next to your notes on this side ELASTIC POTENTIAL ENERGY NOTES When you stretch an elastic or a spring, it wants to return to its unstretched or equilibrium position. The force needed to stretch the spring or elastic depends on: This is called the. The letter stands for the spring constant. The formula to find k is: The potential energy stored in a spring or elastic depends on: So the formula to find PE elastic is: When a force of 30 Newtons is applied to a spring, it moves a distance of 0.5 meters. What is the spring constant? How much potential energy is there in a spring that is stretched 0.5 meters, if the spring constant is 60 N/m? How much potential energy is there if you stretch the spring 2 times as far? (1.0 meters) How much potential energy is there if you stretch the spring 3 times as far? (1.5 meters)

4 4 SECTON 5.1 Reading Guide What is kinetic energy? (1) 2. Write the formula for kinetic energy and tell what each letter means. (4) 3. The unit for kinetic energy is the same as the unit for what? (1) 4. In SI, kinetic energy is measured in what? (1) 5. What are the English units for energy? (1) 6. Kinetic energy increases with the mass. Give an example. (2) 7. Kinetic energy increases with the of the speed. Give an example (2) 8. Look at Example 5.1 then solve the following: After a serve, a 0.27 kg volley ball is moving 20 m/s. What is the kinetic energy of the ball? (4) SKIP FROM PAGE 233 TO 244 SECTION 5.2 Reading guide pp When you toss a ball in the air, you give it energy. (1) 2. At the highest point it stops moving upwards. Its kinetic energy is what? (1) 3. What force causes the ball to stop and then come back down? (1) 4. As the ball rises, it gains the to do work. (1) 5. The amount of work the ball can do because of its height above your hand is called what? (1) 6. Write the formula to find gravitational potential energy and tell what the letters mean. (4) 7. What are the units for potential energy in SI and English? (2) 8. In calculation of gravitational potential energy, the height h is measured from what? (1) 9. When you specify a reference level, you are defining the potential energy to be what? (1) 10. An object or fluid has potential energy because of its position in the Earth s what? (1)

5 5 11. It is more accurate to say the has potential energy. (1) 12. Explain how the forces of the Earth and an object interact. (2) 13. What is restoring force? (1) 14. What is elasticity? (1) 15. The elasticity of a spring is due to what? (1) 16. What is the equilibrium position? (1) 17. What happens when you push or pull a spring from the equilibrium position? (1) 18. Most springs exert restoring forces that are what? (1) 19. What happens if you compress or extend a spring past the elastic limit? (1) 20. What does the spring constant tell you? (1) 21. Work is stored in a spring as what? (1) 22. Write the formula to find Elastic Potential Energy and tell what the letters mean. (4) 23. Give 4 examples of uses for elastic potential energy. (4) 24. Total energy is not lost, it is what? (1) 25. Write the law of conservation of energy. (1) 26. Explain how conservation of energy applies when you toss a ball straight up in the air. (3)

6 6 REVIEW QUESTIONS / 83 POINTS 1. A pile driver hammer stores 100 ft lb of potential energy when the hammer is raised 0.25 ft. How much does the hammer weigh? (show work - 4pts) 2. A block with a mass of 10 kilograms is located 30 meters above a road. If the block fell, what would be its kinetic energy at the moment it struck the ground? Gravity = 9.8 m/sec 2 (assume no losses from air friction) (show work - 4pts) (solve for potential energy which converts to kinetic) 3. A system has a total energy of 600 ftlb. If there are no losses of heat, and 250 ftlb is potential energy, describe the amount and type of energy remaining in the system. (2pts) 4. A construction elevator raises a 300 pound load of bricks from the ground to the third floor of the building, 24 feet above the ground. Find the potential energy of the load of bricks when it reaches the third floor. (show work 4pts) 5. A newspaper printing machine uses a set of rollers to feed paper through the machine. The rollers are held firmly against the paper by a spring. The spring exerts a force of 100 pounds when it is compressed 0.25 feet beyond its upstretched length. a. Find the spring constant (k) that the maintenance technician should specify when ordering a spare replacement. (show work 4pts) b. Find the amount of potential energy stored in the spring when it is compressed the spring 0.25 feet. (show work 4pts) 6. Determine the kinetic energy of a 1000-kg roller coaster car that is moving with a speed of 20.0 m/s. (show work 4points) 7. If the roller coaster car in the above problem were moving with twice the speed, then what would be its new kinetic energy? (show work 4points)

7 7 8. Data showing typical ball speeds for different sports: Fill in the kinetic energies of each ball just after it is struck. (6 pts) KE = ½ mv 2 Ball Ball mass Ball velocity KE (J) (kg) (m/s) before (m/s) after After ball is struck Tennis ball Squash ball Hand ball Golf ball Football kick Cricket ball (Data taken from : Physics, R. Hutchins, University of BATH, Thomas Nelson & Sons Ltd., 1992) 9. Knowing that the potential energy at the top of the tall platform is 50 J, what is the potential energy at the other positions (A-F) shown on the stair steps and the incline? (Each step is the same height) (12 points) Label on the chart for each step. Assuming there are NO losses of energy due to friction, what is the Kinetic Energy at Positions A? C? E? F?

8 8 10. A student does an experiment to see how raising the height of a ramp affects how much potential energy a toy car has at each height, and how much kinetic energy the car has at the bottom of the ramp. The mass of the toy car is 10 kg (remember gravity is 9.8 m/s 2 ) Fill in the correct energy in the chart below (9pts) Height in Meters GPE in Joules (mgh) Velocity m/s KE in Joules ½ mv 2 Difference Between GPE and KE m/s m/s m/s 11. The chart shows that not all of the potential energy at the top of the ramp turned into kinetic energy at the bottom of the ramp. Where did the rest of the energy go? (1pt) 12. A person is going bungee jumping off of a tower. Sketch a picture of the bungee jump to the right. (1pt) Identify each of the following on your sketch. (You can draw an arrow pointing to the part of your sketch that fits.) A. Maximum Gravitational Potential Energy (1pt) B. Where you have both GPE and KE (1pt) C. Maximum Elastic Potential Energy (1pt)

9 9 13. Classify each of the following according to the type of energy. (1 pt. each 11 total) 1. Water in a reservoir behind a dam. A. Gravitational Potential 2. Hydrogen found within the sun. 3. Batteries for a CD player. B. Elastic Potential C. Chemical Potential 4. Rock on a cliff. D. Electrostatic Potential 5. A stretched scale spring. 6. A flywheel that is spinning. E. Nuclear Potential F. Kinetic Energy 7. A bungee cord, when the jumper is at the lowest position, and the cord is stretched 8. A pendulum at the bottom of its swing. 9. When positive and negative charges are separated from one another in a capacitor. 10. A skier sliding down a hill. 11. Rubbing a balloon through your hair, then holding it a few centimeters to the side of your hair. Energy converted to Heat can leave a system in three different ways, define each below: and apply to the examples (1pt each) 14. Define Conduction: 15. Define Convection: 16. Define Radiation: MATCHING: Match which type of heat transfer is mostly responsible for each of the following Choose from: A. Conduction B. Convection C. Radiation 17. The air near the ceiling is normally warmer than air near the floor. 18. You feel the heat from a bonfire even though you are several meters away from it. 19. You can boil water in a microwave oven. 20. Smoke rises up a chimney. 21. The handle of a metal spoon becomes hot when you use it to stir hot soup. 22. Heat lamps over the Pizza s keep them warm. 23. You pound with a hammer on a nail. Both the hammer and the nail get warm.