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## Homework Statement

At the bottom of a hill, a box has a speed of 15 m/s. The hill forms an angle of 30 degrees with the horizontal. How far up the incline of the hill does the box slide?

## Homework Equations

My answer:

d = (vf

^{2}+ vi

^{2}) / 2a

## The Attempt at a Solution

vi = 15 m/s

vf = 0 m/s

a = (-9.81 m/s

^{2})*cos(30) = -8.49 m/s

^{2}

d = 13.25 m

However, the answer key says d = 23 m. This is the answer if you use a = (9.81 m/s^2)*sin(30) instead. Help?