An athlete of mass, M, is undergoing a jump test in your lab. You place accelero
ID: 1416520 • Letter: A
Question
An athlete of mass, M, is undergoing a jump test in your lab. You place accelerometers on the athlete center of mass, and then have her stand on a force sensor plate.
a. What force will the plate reads out when the athlete is standing on the plate without moving?
b. You now have the athlete do a jump by crouching down and then pushing up. While the athlete is pushing up you observe that the acceleration of her center of mass is a constant, A, in the upward direction for a time, t, until her feet leave the plate. What force will the plate measure during this upward motion?
c. Based on the data in the previous part, how low did the athlete crouch? You can assume the athlete’s feet leave the plate when she is in a standing position.
d. What is the maximum height the athlete’s center of mass achieves during the jump?
Explanation / Answer
Here the plate reads Normal force
a) net force acting on the athlet, Fnet = 0
N - M*g = 0
N = M*g
b) net force acting on the athlet, Fnet = M*A
N - M*g = M*A
N = M*(g+A)
c) d = 0.5*A*t^2
d) velocity of athlet when he leaves plate, v = A*t
so, maximum height reahed, Hmax = v^2/(2*g)
= A^2*t^2/(2*g)