Change in gravitational potential energy and work done against gravity

[Amber3046]

Homework Statement

a 46.0kg child cycles up a large hill to a point that is vertical distance of 5.25m above the starting position find:
a.) The change in the childs gravitational potential energy
b.) The amount of work done by the child against gravity

Homework Equations

delta Eg=mg delta h?
W=delta Eg-g?

The Attempt at a Solution

delta Eg=(46.0kg)(9.80m/s2)(5.25m)
delta Eg=2366.7 J {This number seems too high though, and it wouldn't be the change. I don't know how to get that}
W=2366.7-9.80
W=2356.9J

 

[Thaakisfox]

The first part is ok, that is the change..

But for the second part, are you sure can do that??
Check the units..., you are subtracting joules from m/s^2

 

[Amber3046]

The first part is ok, that is the change..

But for the second part, are you sure can do that??
Check the units..., you are subtracting joules from m/s^2

I don't know if you can do that. It was just my guess, do you know how to do that?

 

[tnutty]

what is the formula for the amount of work done that's given in your book. Write all of them

 

[Thaakisfox]

Well of course you can't do that. What was your line of thought that got you there? Maybe we can clear it up then ;)

 

[Amber3046]

Well of course you can't do that. What was your line of thought that got you there? Maybe we can clear it up then ;)

My line of thought was that I would take the Gravitational Potential Energy and subtract the acceleration of gravity (9.81m/s^2). I don't think that it's right, that was just something I tried.