- #1

dlthompson81

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## Homework Statement

A block is at rest on the incline shown in the figure. The coefficients of static and kinetic friction are µs = 0.67 and µk = 0.57, respectively. The acceleration of gravity is 9.8 m/s^2. What is the frictional force acting on the 42 kg mass? Answer in units of N.

## Homework Equations

F=MA

f=µn

## The Attempt at a Solution

Ok, I thought I understood this one, but when I entered it in the answer was wrong. Here is what I got. Thanks in advance for the help.

MG = 9.8 * 42 = 411.6N

Weight of block in Y direction = 411.6cos31 = 352.810061N

Force down the incline = 411.6sin31 = 211.9896716N

Force down the incline minus friction =

411.6sin31 - µ411.6cos31 = 0

µ411.6cos31 = 411.6sin31

µ = 411.6sin31/411.6cos31

µ = 0.6008606189 N

I entered in 0.6008606189 and it was wrong. Where did I go wrong?