1. Physics 101 MFA Chapter 7. Example 1 Two identical balls are dropped from the same height onto the floor. In case 1 the ball bounces back up, and in case 2 the ball sticks to the floor without bouncing. In which case is the impulse given to the ball by the floor the biggest? [See conceptual example 3] 1. Case 1 2. Case 2 3. The same The impulse-momentum theory says that the impulse that acts on an object is given by the change in the momentum of the object, and this change is proportional change in velocity. The ball that sticks has a velocity of downward to zero, but the velocity of the ball that bounces goes downward then upward. This change in momentum is greater and therefore has a greater impulse on it. correct

2. Physics 101 MFA Chapter 7. Example 1 In both cases of the above question, the direction of the impulse given to the ball by the floor is the same. What is this direction? 1. Upward 2. Downward time correct

3. Physics 101 MFA You drop an egg onto 1) the floor 2) a thick piece of foam rubber In both cases, the egg does not bounce. In which case is the impulse greater? A) case 1 B) case 2 C) the same In which case is the average force greater A) case 1 B) case 2 C) the same correct

4. Physics 101 MFA Chapter 7. Example 2. Is it possible for a system of two objects to have zero total momentum while having a non-zero total kinetic energy? 1. YES 2. NO the example of the ice skaters starting from rest and pushing off of each other...the total momentum is zero because they travel in opposite directions but the kinetic energy is not zero (they start with none and gain a bunch) if the objects have the same mass and velocities that cancel each other out, the total momentum is zero. but they still have kinetic energy, because they are moving, and the velocities are squared there so direction doesn't matter. correct

5. Physics 101 MFA Chapter 7. Example 3. Movies often show someone firing a gun loaded with blanks. In a blank cartridge the lead bullet is removed and the end of the shell casing is crimped shut to prevent the gunpowder from spilling out. When a gun fires a blank, is the recoil greater than, the same as, or less than when the gun fires a standard bullet? 1. greater than 2. same as 3. less than If there is no bullet then p bullet = 0 so p gun = 0 correct p gun = -p bullet As if ice skater had no one to push…