An 18.8kg box is released on a 38.0o incline and accelerates down the incline at 0.281m/s2. What is the magnitude of the friction force impeding its motion.(adsbygoogle = window.adsbygoogle || []).push({});

F = m*g*cos(38)

sum forces parallel to the plane

m*g*sin(38) - (mu)*(F) = m*a, or

m*g*sin(38) - (mu)*m*g*cos(38) = m*a

masses cancel out

[9.81*sin(38)-(.281)]/[9.81*cos(38)] = .75 = mu

but it says i'm wrong. i cant be.

i only have one try left, and that's it.

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# Homework Help: Frictional force

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