- #1

szimmy

- 35

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## Homework Statement

The "force platform" is a tool that is used to analyze the performance of athletes by measuring the vertical force as a function of time that the athlete exerts on the ground in performing various activities. A simplified force vs. time graph for an athlete performing a standing high jump is shown in Figure P6.66. The vertical divisions of the graph represent 0.65 kN and the horizontal divisions represent 0.50 s. The athlete started the jump at t = 0.0 s. How high did this athlete jump?

Picture of graph: http://www.webassign.net/sercp/p6-66alt.gif

## Homework Equations

J = FΔt

J = ΔP

J = m(vf - vi)

FΔt = mvf (since the jump starts from rest)

## The Attempt at a Solution

From the graph I was able to get that the impulse is 650N. The problem is I have no idea how to use this to get the height he jumped, I feel like I need a mass to solve this.

Given that J = m(vf - vi)

This means that FΔt / m = vf (vi is 0 because starting from rest)

This vf would be the vi for the jump, so mgh = 1/2 m v^2

h = v^2/2g

h = (650/m)^2/2g

h = 422500 / 2*g*m^2

I'm stuck from here, none of my classmates could figure it out either. If somebody could give me a push in the right direction I would appreciate it. I feel like the solution is obvious and I'm just thinking too hard.

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