1. A 0.140 kg baseball is pitched toward home plate at 30.0 m/s. The batter hits the ball back (opposite direction) to the pitcher at 44.0 m/s. Assume that towards the home plate is positive. What is the change in momentum for the ball? a -8.2 kg*m/s b 1.96 kg*m/S C -10.4 kg*m/S d -20.4 kg*m/s 2. A sprinter with a mass of 76.0 kg can accelerate from 0.0 to 9.0 m/'s in 2.5 seconds. Find the average force the sprinter's legs must exert to cause this acceleration. a 270N b 570N c 260n d 310N 3. If a force of 50.0 N acts on a 3.0 kg object for 2.0 seconds, what will its change in velocity be? a 70 m/s b 33 m/S C 150 m/s d 75 m/s4. A 10,450 kg freight car is rolling along a track at 3.0 m/s. Calculate the time needed for a force of 1120 N to stop the car. 3.1 s b 19 s C 9.3 s d 28 s 5. A 5465 kg elephant walks to the west with a velocity of 1.21 m/s. What is the momentum of the elephant? a 5465 kg*m/s east b 6610 kg*m/s west C 980 kg*m/s west d 4520 kg*m/s west 6. A 0.140 kg baseball is pitched toward home plate at 30.0 m/s. The batter hits the ball back (opposite direction) to the pitcher at 44.0 m/s. Assume that towards home plate is positive. If the ball was in contact with the bat for 0.002 seconds, what is the average force the bat exerts on the ball? a -5200 N b -9700 N C-4700 N d-100ON7. A sprinter with a mass of 78.3 kg is running in the positive direction with a velocity of 12.2 m/s. What is the momentum of the sprinter? a 6.41 kg*m/s b 955 kg*m/S C 782 kg*m/s d 923 kg*m/s 8. If a force of 50.0 N acts on a 3.0 kg object for 2.0 seconds, what will its change in momentum be? a 300 kg*m/s b 150 kg*m/s c 100 kg*m/s d 75 kg*m/s9. How does the Impulse-Momentum Theorem explain why we bend our knees when landing after a jump? a) Bending our knees increases the contact time, thus increasing the contact force. b) Bending our knees increases the contact time, thus decreasing the contact force. c) Bending our knees increases the contact time thus eliminating the contact force. d) Bending our knees decreases the contact time, thus decreasing the contact force. 10. A 1.30 kg ball strikes a wall with a velocity of -10.5 m/s. The ball bounces off with a velocity of 6.50 m/s. If the ball is in contact with the wall for 0.0210 seconds, what is the force exerted on the ball by the wall? a) 651 N b) 1050 N C) 22.1 N d) 402 N