- #1

vandersmissen

- 19

- 0

## Homework Statement

[PLAIN]http://rawrspace.com/physics.GIF

## Homework Equations

v=v

_{0}+at

x=x

_{0}+v

_{0}t+(1/2)at

^{2}

W=[tex]\Delta[/tex]K=K

_{2}-K

_{1}

## The Attempt at a Solution

For the first part of this problem I attempted it this way which I think is completely wrong.

I rearranged the first two equations to get 2a(x-x

_{0})=(v

^{2}-v

_{0}

^{2})

Then i multiplied by (m+M) on both sides and ended up with

(m+M)(x-x

_{0})=(1/2)(m+M)(v

^{2}-v

_{0}

^{2})

Which I don't think is what they are looking for. I believe it is because I am using the wrong equations. How would I approach this with the other equations. I know that Gravitational potential energy is U=mg[tex]\Delta[/tex]y and kinetic energy is (1/2)mv

^{2}

I also know that if a free body diagram were drawn , you would have the tension set equal for them (however it doesn't start at rest so this might not be true, correct ?) that would give you mg[tex]\Delta[/tex]y = (1/2)mv

^{2}+ W

_{f}

where W

_{f}is the work done by friction.

I know total work in the system is W

_{g}= W

_{a}- W

_{f}

I just feel like this has confused me quite a bit and I am not sure which route to approach it from. If someone could shed some light on how to do this problem and how to determine the work done by gravity and friction, I would appreciate it.

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