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Question :
16. Rita accelerates a 0.40-kg ball from rest to 9.0 : 2102101

16. Rita accelerates a 0.40-kg ball from rest to 9.0 m/s during the 0.15 s in which her foot is in contact with the ball. What average force does she apply to the ball during the kick?

A. 48 N

B. 72 N

C. 24 N

D. 60 N

17. A 70.0-kg man jumps 1.00 m down onto a concrete walkway. His downward motion stops in 0.0200 seconds. If he forgets to bend his knees, what force is transmitted to his leg bones?

A. 15 500 N

B. 7 010 N

C. 4 900 N

D. 3 500 N

18. The accelerating force of the wind on a small 200-kg sailboat is 707 N northeast. If the drag of the keel is 500 N acting west, what is the acceleration of the boat?

A. 1.5 m/s^{2} due east

B. 2.5 m/s^{2} due north

C. 3.0 m/s^{2} northeast

D. 2.0 m/s^{2} north by northwest

19. A barefoot field-goal kicker imparts a speed of 30 m/s to a football at rest. If the football has a mass of 0.50 kg and time of contact with the football is 0.025 s, what is the force exerted on the foot?

A. 190 N

B. 380 N

C. 600 N

D. 900 N

20. An automobile of mass 2 000 kg moving at 30 m/s is braked suddenly with a constant braking force of 10 000 N. How far does the car travel before stopping?

A. 45 m

B. 90 m

C. 135 m

D. 180 m