Homework Procedure: Read pages specified in Honors Physics Essentials by Dan Fullerton. Questions labeled TQ will be questions about the text you read. These TQ s can be answered in one word, one phrase, or a complete sentence. Questions labeled CQ are conceptual questions and must be answered in complete sentences. Questions labeled QQ s are quantitative questions and the equation, substitution with units, and solve with units must be shown on your paper. CQ s and QQ s will be similar to the questions found in the Honors Physics Essentials textbook. Read Page 88 (Defining Momentum) TQ1. What is the energy of motion called? TQ2. What collisions all about? TQ3. Why can t you stop a car going 60 mph? TQ4. What is the symbol for momentum? TQ5. What are two types of objects that have a lot of momentum? TQ6. What is the equation for momentum? TQ7. What are the units of momentum? CQ8. A train and a bird are both moving with the same velocity of 50 m/s. Compare their momenta. CQ9. The magnitude of momentum of an object is 50 kg m/s. If the velocity is halved, the magnitude of momentum of the object will be what? QQ10. A tennis ball, with a mass of 0.060 kg, may leave the racket on a serve with a speed of 55 m/s. What is the tennis ball s momentum? CQ11. Which color carts in the table below have the same inertia? Which have the same momentum? Cart Color Cart Mass (kg) Cart Speed (m/s) Red 4 kg 3 m/s Yellow 5 kg 5 m/s Green 5 kg 3 ms Blue 6 kg 2 m/s
Read Page 90 (Impulse) TQ12. What is the change in momentum called? TQ13. What quantity is represented by the symbol J? TQ14. What are the units of J? QQ15. A ball initially at rest is now found to be moving with a momentum of 10 kg m/s. What impulse was applied? QQ16. A 2 kg cart was moving at 2 m/s forward and changed its velocity to 5 m/s in the same direction. What is the magnitude of the impulse of the cart? QQ17. A 5 kg block is sliding to the right across a horizontal, frictionless surface with a velocity of 4 m/s. The block strikes an obstacle that exerts an impulse of 10 kg m/s to the left on the block. What is the new momentum of the block (including direction) after the collision? What is the new speed of the block after the collision? CQ18. What are two quantities that have units of kg m/s? CQ19. If a cart experiences an impulse of 100 kg m/s, what was the change in momentum of the cart?
Read Page 91-92 (Impulse-Momentum Theorem) Physics Momentum TQ20. If impulse equals the change in momentum, what else does it equal to? TQ21. What is the equation for the Impulse-Momentum Theorem? TQ22. If an airbag in a car acts on a person s face over a period of time, what is this also known as? QQ23. A person applies a force of 200 N on a 5 kg block for a period of 4 seconds. What is the magnitude of the change in the car s momentum? QQ24. If the block in QQ23 starts from rest, what is the block s final speed? QQ25. A 10 kg box is initially moving at 6 m/s to the right. If a constant force of 5 N in the same direction to the right is applied for 4 seconds, what is the final speed of the box? QQ26. A baseball of mass 0.20 kg is traveling at 40 m/s. The catcher must exert an 800 N of force to bring the baseball to a rest. How much time did it take for the baseball to come to rest? QQ27. A 2 kg cart is traveling 4 m/s to the right. It hits a wall and bounces the opposite direction (to the left) and is now traveling 2 m/s. If the wall and cart were in contact with 0.005 seconds, what was the average force the wall exerted on the cart? QQ28. A 5 kg block was dropped on the ground. The instant before it hit the ground it was traveling 3 m/s. The force on the ground to bring the block to a stop was found to be 300 N. How much time did it take to bring the block to a stop? Read Page 94 (Non-Constant Forces) TQ29. How do you find the impulse applied on an object if you have a Force-time graph? QQ30. What is the impulse from 2 4 seconds on the graph above? QQ31. What is the change in momentum from 7 10 seconds in the graph above? QQ32. If the graph above is a force-time graph of a 2 kg cart, what would the velocity be of that cart after the first 2 seconds on the graph if it started from rest?
Read Pages 94-95 (Conservation of Momentum) Physics Momentum TQ33. In an isolated system, what can be said always about momentum? TQ34. Write the equation for the law of conservation of momentum? TQ35. Where does this law of conservation of momentum come from? TQ36. When analyzing collisions and explosions, what can you use to help you out? QQ37. An 8 kg cart is traveling at 4 m/s and collides with a 4 kg cart at rest. If the 8 kg cart is traveling 2 m/s in the same original direction after the collision, what velocity is the 4 kg cart moving after the collision? QQ38. An 50 kg bumper car is moving north at 12 m/s and hits another bumper car with a mass of 40 kg headon. As a result of the collision, both bumper cars get locked together and immediately come to a stop. What is the speed and direction of the 40 kg bumper car before the collision? CQ39. A 0.75 kg hammer traveling at 40 m/s hits a 0.006 kg nail at rest. The hammer hits the nail with a force of 800 N. Determine the magnitude of the force that the nail exerts on the hammer during the collision. CQ40. A red sphere of mass M R is moving to the right at a velocity V. The red sphere collides with a blue sphere of mass M B which is at rest. Upon collision, the two masses stick together. Determine the algebraic equation to find the final velocity V F of the two spheres when they stick together (only use variables in your answer). QQ41. Two students facing each other are wearing ice skates and standing on a frictionless surface of ice both at rest. A girl of mass 60 kg pushes a boy of mass 80 kg. The boy travels to the right at 6 m/s. What speed and direction does the girl travel? QQ42. The diagram above shows two carts initially at rest on a horizontal, frictionless surface tied together by a string. There is compressed spring between the two carts. Cart A has a mass of 2 kg and Cart B has a mass of 1 kg. When the string is cut, Cart B moves to the right at a speed of 0.76 m/s. What speed and direction will Cart A move? CQ43. A 1.0 kg cart (shown above) is traveling to the right at 8 m/s. While it is moving, a 1.0 kg weight is dropped on the top. Did the speed of the cart increase, decrease, or stay the same? Did the momentum of the cart increase, decrease, or stay the same?
Read Page 99 (Types of Collisions) TQ44. What kind of collisions occurs when objects bounce off of each other? TQ45. What is the primary difference between an elastic collision and an inelastic collision? TQ46. What is ALWAYS conserved whether it is an elastic or inelastic collision? QQ47. Cart 1 (2 kg) is moving with a velocity of 4 m/s to the right. Cart 2 (also 2 kg) is at rest. Both carts collide together and after the collision, Cart 1 immediately comes to a stop. What is the velocity of Cart 2 after the collision? Is this collision elastic or inelastic? Justify your answer with a calculation. QQ48. Cart 1 (5 kg) is moving with a velocity of 12 m/s to the right. Cart 2 (4 kg) is at rest. Both carts collide and stick together after the collision. What velocity are both cars (now one large mass) moving after the collision? Is this collision elastic or inelastic? Justify your answer with a calculation. CQ49. A truck and a compact car are traveling down the road with the same momentum. Which is moving a faster velocity? CQ50. The truck and the compact car in CQ49 are now brought to a rest with an applied force of the brakes. If both objects (the truck and the compact car) take an equal amount of time coming to a stop, which one needs to apply more force the truck, the compact car, or neither?
Free Response Momentum Problem A 70 kg woman and her 35 kg son are standing at rest on an ice rink, as shown above. They push against each other for a time of 0.60 seconds, causing them to glide apart. The speed of the woman immediately after they separate is 0.55 m/s. Assume that during the push, friction is negligible with the forces the people exert on each other. (a) Calculate the initial speed of the son after the push. (b) Calculate the magnitude of the average force exerted on the son by the mother during the push. (c) How do the magnitude and direction of the average force exerted on the mother by the son during the push compare with those of the average force exerted on the son by the mother? Justify your answer.