# Homework Help: Finding height using Conservation of Energy

1. Oct 5, 2008

### Kajayacht

1. The problem statement, all variables and given/known data
A skier (m=61.00 kg) starts sliding down from the top of a ski jump with negligible friction and takes off horizontally. If h = 6.70 m and D = 9.80 m, find H.

I already found the velocity as he leaves the cliff to be 29.2 m/s

Here's a picture of it: http://img264.imageshack.us/my.php?image=prob21agz5.gif

2. Relevant equations
E[1] + W[non conservative] = E[2]
K= .5mv^2
U= mgh

3. The attempt at a solution

w[nc]= 0 (no friction)
K[1]= 0, U[2] = 0 so K[2] = U[1]

K[2]= .5*61*29.2^2
K[2]= 26005.52

26005.52 = mgH
26005.52/ (61*9.8) = H
H=43.5

2. Oct 5, 2008

### hage567

Can you show how you got this? That's a pretty high speed.

3. Oct 5, 2008

### Kajayacht

You're right, and after reworking I found the speed to be 8.38 m/s which gave me the right answer

4. Oct 5, 2008

### Kajayacht

which I found using V= d* (square root of( g/2h))

5. Oct 5, 2008

### hage567

That looks much better!