Posted by neosha on Thursday, June 24, 2010 at 12:02am.
An 80kg man walks down a ramp that makes a 40 degree angle with the horizontal. By how much does his gravitational potential energy change (in kJ) when he walks 15m down the ramp?

college physics  Quidditch, Thursday, June 24, 2010 at 12:41am
gravitational potential energy = mgh
where:
m = mass
g = gravitational acceleration
h = height
So, the change in gravitational potential energy is:
delta p = 80kg * 9.8m/sec^2 * (h1  h2)m 
college physics  neosha, Thursday, June 24, 2010 at 1:05am
Thank You but I still do not understand what I should do with the angle as far as finding the height is concerned

college physics  Quidditch, Thursday, June 24, 2010 at 1:25am
OK, the ramp makes a 40 degree angle with the horizontal. A sketch might help visualizing this. If you move 15m down the ramp what is the change in the y direction (the height)? It is 15m * sin(40degrees).
So, the potential energy change is:
=(80kg) * 9.8m/sec^2 * ( 15m * sin(40degrees)). Remember that the answer should be in KJ. 
college physics  Dr Russ, Thursday, June 24, 2010 at 6:20am
Remember that the answer should be in KJ. I think you mean kJ.

college physics  Quidditch, Thursday, June 24, 2010 at 10:36am
Yes, thanks!