Finding height using Conservation of Energy

AI Thread Summary
The discussion focuses on calculating the height (H) from which a skier takes off horizontally after sliding down a ski jump. The skier's mass is 61 kg, and the height from which they start is 6.70 m, with a horizontal distance of 9.80 m. Initially, a velocity of 29.2 m/s was calculated, but this was later corrected to 8.38 m/s using the formula V = d * sqrt(g/2h). The conservation of energy principles were applied, with kinetic energy equating to gravitational potential energy to find the correct height. The final calculations confirmed that the correct height is significantly lower than initially thought.
Kajayacht
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Homework Statement


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

Homework Equations


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


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

Can you show how you got this? That's a pretty high speed.
 
You're right, and after reworking I found the speed to be 8.38 m/s which gave me the right answer
 
which I found using V= d* (square root of( g/2h))
 
That looks much better!
 
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