- #1

timnswede

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## Homework Statement

Starting from rest, a 65 kg athlete jumps down onto the force platform from a height of .6 m. While she is in contact with the platform during time interval 0s-.8s, the she exerts on it is described by the function F=9200t-11500t^2 where F is in N and t is in s.

a) What impulse did the athlete receive from the platform?

b) With what speed did she reach the platform?

c) With what speed did she leave it?

d) To what height did she jump upon leaving the platform?

## Homework Equations

I=∫ΣFdt

kinematic equations

I=ΔP

ΔP=MVf-MVi

## The Attempt at a Solution

For part a) i just integrated and got I=983.

For part b) I used kinematic equations and got v=3.43 m/s.

Part c and d I am confused how to solve them. For part c) I did I=ΔP, 983=65Vf-65(3.43)= 18.5 m/s which seems like it would be way too high, but I used that for part d) where I did .5mv^2=mgh and I ended up with 17.5m which I am assuming is way wrong.

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