Aims: February 2, 2017 SWBAT identify their current mastery of Forces SWBAT obtain an 80% or higher on their Forces Unit Test. Agenda 1. Do Now 2. Independent Practice 3. Practicing our AIMS: F.18 - Review Analysis How will you help our class earn all of our S.T.R.I.V.E. Points? Which famous black actor provided the voice for Darth Vader in the original Star Wars films? Unit test countdown: 3 Study Days! 1
James Earl Jones! Actor James Earl Jones was born on January 17, 1931, in Arkabutla, Mississippi. As a child, Jones developed a severe stutter, which he overcame during his high school years. He went on to star in a long list of successful movies and plays, becoming widely known as the voice of Darth Vader in the Star Wars film franchise. o Known for his humility, he declined to have his name appear on the credits of both Star Wars: Episode IV - A New Hope (1977) and Star Wars: Episode V - The Empire Strikes Back (1980), claiming that he felt his contribution wasn't significant enough to warrant a credit. He did agree to have his name appear of the credits of Star Wars: Episode VI - Return of the Jedi (1983). Jones won Tony Awards for his performances in The Great White Hope and Fences, and garnered an honorary Academy Award in 2011. He is also a two-time Emmy Award winner. 2
SCIENCE 8 Forces Review F.18 Name: Date: Homeroom: REVIEW OBJECTIVES: By the end of review, students will be able to SWBAT identify their current mastery of Forces SWBAT obtain an 80% or higher on their Forces Unit Test. DO NOW Directions: Review the following excellent examples of an effective review analysis. Identify at least one characteristic for each example that makes it effective. 3
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1. Compare and contrast contact and field forces FORCES (5 points) 2. Define friction and explain its effect a moving object. 3. Explain why inertia is not a force. 5
FORCE BODY DIAGRAMS ( 6 Points) 4. A 2.0 kg block sits at rest on a frictionless horizontal surface. Describe the motion of the block when two forces are applied as shown in the diagram. Justify your reasoning. 5. A battery-powered toy submarine is moving through water at constant speed and at a constant depth below the surface. The diagram shows the submarine with arrows representing the directions but not the magnitudes of four forces acting on it. What conclusion can be made about the magnitudes of the forces acting on the submarine? 6
7. A force is applied to accelerate a crate across a rough horizontal surface. Draw the force body diagram; label all forces acting on the crate. 8. The picture below shows the four major forces acting on an airplane in flight. What causes the force indicated by the X? 9. A book rests on top of a table. Draw the force body diagram; label all forces acting on the book. 7
10. A bucket of water, attached by a rope, is being pulled out of a well. Draw the force body diagram; label all forces acting on the bucket. NET FORCE ( 8 Points) 11. A basket of apples is pulled with a constant force. A friction force acts in a direction opposite to the motion. The basket starts at rest and increase its speed over time Describe three actions that will increase the rate at which the speed of the basket changes. 12. What will happen to an object s motion over time if no new forces are applied? 8
10. Four children pull on the same toy at the same time, yet there is no net force on the toy. How is that possible? 11. Explain how force, mass and acceleration are related by Newton s second law of motion. 12. For each experiment, students measure: The mass of the carts The amount of force applied to the carts The speed of the carts after 10 seconds. Trial Mass of Cart (g) Applied Force (N) Final Velocity (m/s) 1 2,000 40 15 2 2,000 20 4 3,500 40 Estimate the values for the two missing quantities. Write your estimates into the blank boxes in the table. 9
GRAVITATIONAL FIELDS ( 8 Points) 13. Identify the two factors that determine the force of gravitational attraction between two objects and explain how each affects the magnitude of the force experienced. 14. A teacher dropped a feather and bowling ball simultaneously in a vacuum (ignore air resistance). Predict which object will accelerate faster. 15. Compare and contrast weight and mass. 10
16. Predict how a planet s motion would be affected move if the inward force of gravity from the Sun were to suddenly disappear. 17. If the masses of two objects are not changed, but the distance between them is tripled, what happens to the gravitational force? 18. A pencil, coffee mug, and laptop are sitting on Ms. Fagan s desk. Rank the amount of gravitational force of each object experiences. 11
ELECTROMAGNETISM ( 8 Points) 19. A scientist runs on electric current along a wire. A magnetic compass is placed near the wire. The scientist observes that whenever the current is turned on, the compass needle moves. Why does the compass needle move? 20. The diagram shows the placement of four bar magnets within the magnetic field of a larger bar magnet. Which bar magnet will experience the greatest magnetic attraction? Justify your reasoning. 12
21. A large negatively charged particle is placed at a fixed position surrounded by several smaller charged particles, as shown in the diagram. All of the smaller particles have charges that are equal in magnitude. Draw an arrow into each box to predict the strength and direction of force each charge experiences due to the central charge. The lengths of the arrows represent the relative strengths of the forces. Draw only one arrow in each box. 22. A superconductor is capable of using magnetic forces so that it hovers just above the surface of the superconductor. Predict the type of pole interaction that would cause this effect. Justify your answer. 23. Sketch a diagram representing the electric field between two oppositely charged objects. 13
DON T PRACTICE UNTIL YOU GET IT RIGHT, PRACTICE UNTIL YOU CAN T GET IT WRONG! 1. Which cart has the greatest inertia? A. 1-kilogram cart traveling at a speed of 4 m/s B. 2-kilogram cart traveling at a speed of 3 m/s C. 3-kilogram cart traveling at a speed of 2 m/s D. 4-kilogram cart traveling at a speed of 1 m/s 2. At the circus, a 100.-kilogram clown is fired at 15 meters per second from a 500.-kilogram cannon. What is the recoil speed of the cannon? A. 75 m/s B. 3.0 m/s C. 15 m/s D. 5.0 m/s 3. The diagram shows a 5.00-kilogram block at rest on a horizontal, frictionless table. Which diagram best represents the force exerted on the block by the table? A. B. C. D. 14
4. Which pair of graphs represent the same motion? A. B. C. D. 5. When you drop a rock from a cliff, which of the following happens? A. Only the rock falls to the Earth B. Only the Earth falls up to meet the rock C. The rock and the Earth fall towards each other D. None of the above 6. If you place two teenagers with equal mass in space: A. They will fall towards each other B. They will remain in place C. They will move apart D. We cannot even make an educated guess about what will happen 7. What is gravity? A. What goes up must come down B. Everything is attracted to everything else C. Only small things are attracted to larger things D. Only larger things are attracted to smaller things 15
8. Why do astronauts weigh less on the moon than they do on the earth? A. It's a little known fact, but space suits generally make people weigh less. B. The moon has less mass than the Earth. Therefore, it has a smaller gravitational pull on the astronaut. C. The Earth is closer to the sun. D. Astronauts weigh the same no matter where they are. 9. What causes gravity? A. The force of magnetism. B. The amount of electrons in a particular object. C. We don't know, conclusively. D. Scientist determined the amount that objects are attracted to one another. 10. Electrical forces. A. can cause objects to only attract each other B. can cause objects to only repel each other C. can cause objects to attract or repel each other D. have no effect on objects 11. An electrically neutral atom is an atom which. A. does not have any protons or electrons B. has the same number of protons and electrons C. has the same number of neutrons and electrons D. has the same number of protons, electrons and neutrons 16
Science 8 Name: SKILL SNAPSHOT Date: Homeroom: F.18: Review Analysis Quick Notes: Like A Scholar? Yes No Redo? Yes No MY OVERALL SCORE IS out of 35 My current skills show (circle your score): Mastery (28-35) Progressing (25-27) Not Yet (0-24) CONCEPT : Parts I Could Do BY MYSELF FORCES Concepts I Needed REMINDING to do Grade earned Mastery ( 4-5 ) Progressing ( ) Not Yet ( 0-3 ) Describe one way you will improve your answers for next time. CONCEPT : Parts I Could Do BY MYSELF FORCE BODY DIAGRAMS Concepts I Needed REMINDING to do Grade earned Mastery ( 5-6 ) Progressing ( ) Not Yet ( 0-4 ) Describe one way you will improve your answers for next time. 17
CONCEPT : Parts I Could Do BY MYSELF NET FORCE Concepts I Needed REMINDING to do Grade earned Mastery (7-8) Progressing (6 ) Not Yet ( 0-5 ) Describe one way you will improve your answers for next time. CONCEPT : Parts I Could Do BY MYSELF GRAVITATIONAL FORCE Concepts I Needed REMINDING to do Grade earned Mastery (7-8) Progressing (6 ) Not Yet ( 0-5 ) Describe one way you will improve your answers for next time. CONCEPT : Parts I Could Do BY MYSELF ELECTROMAGNETISM Concepts I Needed REMINDING to do Grade earned Mastery (7-8) Progressing (6 ) Not Yet ( 0-5 ) Describe one way you will improve your answers for next time. 18