Calculate the final speed of a 110-kg rugby player who is initially running at 8.00 m/s but collides head-on with a padded goalpost and experiences a backward force of 1.76×104 N for 5.50×10-2 s .

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees upon landing to reduce the force of the impact. A 69.5-kg man just before contact with the ground has a speed of 8.82 m/s. (a) In a stiff-legged landing he comes to a halt in 4.17 ms. Find the magnitude of the average net force that acts on him during this time. (b) When he bends his knees, he comes to a halt in 0.267 s. Find the magnitude of the average net force now. (c) During the landing, the force of the ground on the man points upward, while the force due to gravity points downward. The average net force acting on the man includes both of these forces. Taking into account the directions of the forces, find the magnitude of the force applied by the ground on the man in part (b).

stretch 38. Realizing that he could not drive up a 30°, ice-covered hill because there was no friction, Sir Isaac Newton had stopped his cart, of total mass 500 kg, at the bottom. He was struck in the rear by a London stage coach, of total mass 1500 kg. trav- elling at 20 m/s. The two vehicles stuck together, with nothing breaking loose, and slid up the hill in a straight line. How far up the slope did the wreckage get before coming to rest? (SIN '70)

Male bighorn sheep (120 kg ) engage in head-butting contests to establish dominance. High-speed photography has shown that the impact speed is typically 6.0 m/s and that the collision, which brings both rams to a halt, lasts approximately 0.25 s . Suppose the collision force increases linearly with time until it reaches a maximum Fmax , then decreases linearly to zero at t = 0.25 s.  What is Fmax?