Chapter 07, Problem 08 Your answer is partially correct. Try again. When jumping

Question

Chapter 07, Problem 08 Your answer is partially correct. Try again. 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 68.9-kg man just before contact with the ground has a speed of 6.50 m/s. (a) In a stiff-legged landing he comes to a halt in 3.09 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 hait in 0.105s.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, force applied by the ground on the man in part (b). find the magnitude of the (a) Numb Unit Units N Units I[ N (b) Numbe 4265 (c) Number LINK TO TEXT By accessing this Question Assistance, you will learn while you earn points based on the Point Potential Policy set by your instructor d estion Attempts: 1 of 15 used savno. ure Points available only if you

Explanation / Answer

a) Momentum = m v = 68.9 * 6.5 = 447.85 kg.m/s

Force = Momentum / time

= 447.85 / 3.09 * 10-3

= 144,935 N

b) Force = 447.85 / 0.105

= 4265 N

c) force of theground on the man in part (b)

Fground = f + weight

= 4265 + (68.9 * 9.8)

= 4940 N

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