# Homework Help: Newtons Law of Motion/Free Falling objct

1. Sep 28, 2006

### baqi

Hi I have a problem I need someone to check over and see if I have it right!

Thank you for trying in advance

Responding to an alarm, a 92kg fireman slides down a pole to the ground floor, 3.2m below. The fireman starts at rest and lands with a speed of 4.9 m/s. Find the average force exerted on the fireman by the pole.

m=92 Kg, d=3.2m, Vf= 4m/s
I found time first: (Can I do that?)
y-vector
y=0.5 (Voy+Vy)t
3.2m =0.5 (0+4m/s)t
t=1.6s

y=yo+Voyt+0.5ayt^2
ay=2(y-yo) / t^2
ay = (2)(0-3.2m) / 1.6s
ay=-4m/s^2

Sum of Fy= F-mg
F-mg=ma
F= may+mg = m(ay+g)
F = (92kg)(-4m/s^2+9.81m/s^2)
F= 534.5N
Thanks

2. Sep 28, 2006

### Noein

Compare the quantities given in the problem to the quantities inserted into the formulas. And watch for exponents.

3. Sep 28, 2006

### baqi

thanks

I think how I solved the above question is wrong because I found time and then solved for accerlation instead of just finding accerlation from the information given and then account for all the forces...

And for the free falling object I forgot what I was going to ask....