MESSAGE MY INSTRUCTOR FULL SCREEN PRINTER VERSION apter 07, Problem 08 hen jumpi

Question

MESSAGE MY INSTRUCTOR FULL SCREEN PRINTER VERSION apter 07, Problem 08 hen 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 rce of the impact. A 72.8-kg man just before contact with the ground has a speed of 4.52 m/s. (a) In a stiff-legged landing he comes to a halt in 4.91 ms. nd 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 0.260 s. Find the magnitude f 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 verage 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 he ground on the man in part (b) (a) Number Units Units Units (b) Number (c) Number LINK TO TEXT Question Attempts: O of 5 used SAVE FOR LATER SUBNIT ANSWER

Explanation / Answer

A) Momentum of the man = Mass x Velocity

= 72.8 x 4.52 = 329.06 kg.m/s

Force = Momentum / Time

In first case,

Time = 4.91 ms = 4.91 x 10^-3 s

So Force = 329.06 / 4.91 x 10^-3 = 67018.33 N

B) In second case, Time = 0.260 s

So Force = 329.06 / 0.26
= 1265.615 N
C) Fground= 1265.615+ 72.8*9.8= 1979.005N

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