Question

An average person can reach a maximum height of about 60 {\rm cm} when jumping straight upfrom a crouched position. During the jump itself, the person's bodyfrom the knees up typically rises a distance of around 50 {\rm cm}. To keep the calculationssimple and yet get a reasonable result, assume that the entirebody rises this much during the jump. In terms of this jumper's weight W , what force does the ground exert on him or herduring the jump?

Answer 1

Answer:

2.2 W where W is the weight of the jumper.

Explanation:

A) use the formula

V^2 = 2gh= 2*9.81*60

that gives

V = 3.43 m/s

b) W = mg

during the jump , the displacement of the body is d =0.5m

so the acceleration a = (V^2-Vo^2)/2d = 11.76 m/s^2

net force applied by ground = m(g+a) = W/g(g+a)

= 2.2 W