Average force if jumping off a building?

[mga2010]

average force if jumping off a building?

Homework Statement

A 75.0-kg stuntman jumps from a balcony and falls 25.0 m
before colliding with a pile of mattresses. If the mattresses
are compressed 1.00 m before he is brought to rest, what
is the average force exerted by the mattresses on the
stuntman?

Homework Equations

Favg=change in power/time

t=square root of (2h)/g

The Attempt at a Solution

t=√((2*25)/9.81)
t=2.258 seconds

Favg=MVf-MVi/2.258
***vf=0 so that cancels out??***
left with: MVi/2.258

***AFTER THAT I'M LOST.***

 

[willem2]

First, calculate the speed of the stuntman just before he hits the matresses. This is your $v_i$

$$F_{avg} = \frac {M v_f - M v_i } {t}$$

is correct, but the time used here is not the 2.258 s falling, but the much shorter time for the stuntman to come to a stop in the matresses.