A cart with a mass of 7.0 kilograms is attached to a spring. When released from the spring, the cart travels up a hill with a height of 12 meters. The cart comes to rest at the top of the hill. The spring is 100% efficient. 4. Approximately how much elastic potential energy was required to bring the cart to rest at the top of the
hill?
A. 42.0 joules
B. 68.7 joules
C. 504 joules
D. 824 joules

16. a brave but inadequate rugby player is being pushed backward by an opposing player who is exerting a force of 800 n on him. the mass of the losing player plus equipment is 90.0 kg, and he is accelerating at 1.20m/s2 size 12{1 "." "20"" m/s" rsup { size 8{2} } } {} backward. (a) what is the force of friction between the losing player’s feet and the grass? (b) what force does the winning player exert on the ground to move forward if his mass plus equipment is 110 kg? (c) draw a sketch of the situation showing the system of interest used to solve each part. for this situation, draw a free-body diagram and write the net force equation.