motion with friction slope

Question

box on slope

slope 3m long

angle of θ with the horizontal, where 15◦ ≤ θ ≤ 50◦

box starts from rest at the top of the slope.

sliding friction is ''mu''=0.2

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Show that the speed (in ms^-1)of the box at the bottom of the slope is given by

sqrt (6g(sinθ − 0.2cosθ))

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can anybody help me with this.

Answer 1

HINT: acceleration on the slope for the object: $g(\sin \theta-\mu \cos \theta)$ and $v^2-u^2=2as$ and here, $u=0 ms^{-1}$ and s=$3m$. Easy to compute?