6. John is on his skates coming home from school with his school bag on his back when he sees his mother and asks her to take the bag. He throws the bag for her to catch and is surprised when he recoils backwards. His school bag has a mass of 8 kg and is thrown with a velocity of 4.5 ms". John's mass, including his skates, is 68 kg. His recoil velocity was about: A. 0.35 ms' B. 0.41 ms' C. 0.49 ms"' D. 0.53 ms- 7. During collisions, it is often acceptable to ignore the force of gravity on an object. his is because a. the time the other forces act is so short that we can ignore the force of gravity b. the force of gravity is always acting on the object and we only consider change c. the object may be in space and the gravitational force does not exist d. the collision is often perpendicular to the force of gravity, so F, does not play a role e. the force of gravity is insignificant compared to the other forces acting on the object 8. A bullet with a mass of 28 g is fired from a 2.8-kg gun that is stationary, but free to recoil. After the bullet is fired, the gun is observed to be moving at 1.4 m/s [left]. The velocity of the bullet is a. 140 m/s [left] d. 71 m/s [left] b. 140 m/s [right] e. 71 m/5 C. 71 m/s [right] 9. An arrow of mass 0.08 kg traveling at 25 m/s [forward] pierces an apple of mass 0.2 kg that was traveling at 5 m/s in the same direction. What is the velocity of the combined arrow/apple immediately after the strike? a. 10 m/s [forward] b. 20 m/s [forward] C. 7 m/s [forward] d. 15 m/s [forward]