# Work done by gravity by Wonder Woman

1. Oct 22, 2012

### venceslau

Work done against gravity by Wonder Woman

1. The problem statement, all variables and given/known data
Wonder Woman, whose mass is 52 kg, is holding onto the free end of a 13.0 m rope, the other end of which is fixed to a tree limb above. She is able to get the rope in motion so that she can reach a ledge when the rope makes a 60 degree angle with the downward vertical axis. How much work does Wonder Woman do against the force of gravity?

2. Relevant equations
W=mgdcos(θ) ...maybe?

3. The attempt at a solution
Honestly, I'm having a hard time even understanding the wording of the problem itself (ESL). Are they telling me she swung over to a ledge, and want me to calculate the work of gravity when she's by that ledge? I don't get it....some insight on what is being asked would be greatly appreciated.

Filipe

Last edited: Oct 22, 2012
2. Oct 22, 2012

### PeterO

I suspect the work done will simply equal the change in Gravitational potential energy compared to hanging vertically, and being on the ledge.

3. Oct 22, 2012

### venceslau

Ohh...I feel so dumb now. lol.
So, will it be just the change in potential energy for Δh?

[STRIKE]So final equation is W=m*g*Δh=m*g*(30-30*cos(θ)) ?[/STRIKE]
So final equation is W=m*g*Δh=m*g*(13-13*cos(θ)) ?

Thanks

Last edited: Oct 22, 2012
4. Oct 22, 2012

### PeterO

I think the figure [rope length] in the original was 13 not 30?
I appreciate the ESL difficulty with written questions.

5. Oct 22, 2012

### venceslau

Thanks for pointing that out! Fixed.
I am the worst for making dumb mistakes like that.

I appreciate your quick reply, I can now finish my homework. :)