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## Homework Statement

Here's the problem :

http://www.diigo.com/item/image/2sb3i/wonu [Broken]

## Homework Equations

Ei = Ef

## The Attempt at a Solution

The surface between A and B is frictionless :

Ei = Ef

K

_{A}+ U

_{A}= K

_{B}+ U

_{B}

mgh

_{A}= 1/2 mv

_{B}

^{2}

v

_{B}

^{2}= 2gh

_{A}= 2*9.8*3 = 58.8 m/s

The surface from C to the spring is frictionless :

Ei = Ef

1/2 mv

_{C}

^{2}= 1/2 kx

^{2}

v

_{C}

^{2}= kx

^{2}/m = 2250*0.32/10 = 20.25 m/s

The surface between B and C has a friction :

Ef - Ei = -f

_{k}d

1/2 mv

_{C}

^{2}- 1/2 mv

_{B}

^{2}= -u

_{k}mgd

1/2 m (v

_{C}

^{2}- v

_{B}

^{2}) = -u

_{k}mgd

1/2 * 10 (20.25 - 58.8) = -u

_{k}*10*9.8*6

u

_{k}= 0.327

Right?

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