- #1

Mad Season

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## Homework Statement

A block is placed on a incline plane. A 21 N force is required to push the block up the incline with constant velocity. What is the weight of the block? Answer in units of N

## Homework Equations

The force pushing the block=21 N with an angle of 13 degrees. The ramp has an angle of 21 degrees. Coefficient of friction=0.17. Ramp goes up from left to right.

fs = uN, F = ma, acceleration is 0.

Angle of force = phi, Angle of ramp = theta

## The Attempt at a Solution

My attempt: (after drawing my free-body diagram)

F(y-component): N-mgcos(theta) = 0 --> N=mgcos(theta) --> Fsin(phi)-mgcos(theta) = 0

F(x-component): Fcos(phi)-mgsin(theta)-fs = 0 --> Fcos(phi)-mgsin(theta)-umgcos(theta) = 0

I multiplied the y-component with the negative u (or mu) to cancel out umgcos(theta)

Then: Fcos(phi)-uFsin(phi)-mgsin(theta) = 0, So I solved for mg and my answer was incorrect. What am I doing wrong? Any help appreciated, thanks.