1. Feb 13, 2008

### nickclarson

1. The problem statement, all variables and given/known data

A box of mass M = 7.68 kg is at rest at the bottom of a frictionless inclined plane.

The box is attached to a string that pulls with a constant tension T = 113 N. Write the general equation that gives the work done by the tension when the box has moved a distance x along the plane. Now, find the speed of the box as a function of x and the angle of the plane. Finally, for a distance of x = 6.38 m and an angle of 30.5°, determine the power delivered by the tension in the string as a function of x.

2. Relevant equations

$$K=\frac{1}{2}mv^{2}$$
$$P=FV$$

3. The attempt at a solution

I know I am supposed to multiply the net force by velocity for the last part, but I need to find the velocity.

I figured I could use kinetic energy to find the velocity using the ke work theorem. So...

$$KE_{f}-KE_{i}=W$$

And since the initial energy is 0

$$KE_{f}=W$$

Am I on the right track?

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Edit: Solved

Here's the final equation I derived:

$$P=T\sqrt{\frac{2x(T-mgsin\theta)}{m}}$$

Last edited: Feb 13, 2008