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## Homework Statement

A small box is at the bottom of a ramp tilted at an angle of 40 degrees above horizontal. The box is given a push and it then slides up the ramp 2.0 seconds before sliding back down. The coefficient of sliding friction is 0.15. Find the time for it to slide back to the point it was released.

## Homework Equations

F

_{net}= ma

## The Attempt at a Solution

a = - gsin[tex]\theta[/tex] - ugcos[tex]\theta[/tex]

a = - 6.41 m/s

^{2}

Up:

v

_{2}= 0

t = 2s

a = - 6.41 m/s

^{2}

d = -(-1/2at

^{2})

d = 12.83 m

Down:

v

^{1}= 0

a = gsin[tex]\theta[/tex] - ugcos[tex]\theta[/tex] = 6.18 m/s

^{2}

d = 12.83 m

t = sqrt(d/(1/2a)) = 2.04 s

The answer is supposed to be 2.4 s.

What'd I do wrong?