How to Calculate Net Impulse from Jumping Motion Analysis

[Trandall]

Homework Statement

A person with a mass of 80.6 kg jumps from a squat position into the air. The velocity
at the beginning of the jump is zero. Fast motion video analysis reveals that the
velocity of the centre of mass at take-off was 5.3 ms-1. Foot contact time when the
ground reaction forces are being generated is 0.25 s. What is the net impulse?

Homework Equations

I = change in p
p = m * v
I = F * t

The Attempt at a Solution

80.6 * 5.3 = 427.18
427.18 * 0.25 = 106.8

Can someone please check this, I think I've made a mistake

Thanks heaps =)

 

[Doc Al]

I = change in p

This is all you need.

80.6 * 5.3 = 427.18
427.18 * 0.25 = 106.8

Why don't you describe what you were doing in each of these calculations? (One makes sense, the other doesn't. )