- #1

- 365

- 0

## Homework Statement

A woman attempts to push a box of books that has mass 36.5 kg up a ramp inclined at an angle 27.5 degrees above the horizontal. The coefficients of friction between the ramp and the box are mu_s and mu_k. The force F applied by the woman is horizontal.

**Assume that mu_s is 0.860 and that mu_k is 0.320. What magnitude of force must the woman apply to keep the box moving up the ramp at constant speed?**

## Homework Equations

acceleration = 0

w = 36.5(9.8) = 357.7

μ

_{s}= f

_{s}/n

μ

_{k}= f

_{k}/n

n - 357.7cos(27.5) - Fsin(27.5) = 0

n=Fsin(27.5)+357.7cos(27.5)

Fcos(27.5) - 357.7sin(27.5) - fs = 0

(fs = μs*n)

## The Attempt at a Solution

I know μ

_{s}= [Fcos(27.5) - 357.7sin(27.5)] / [357.7cos(27.5) + Fsin(27.5)]

I tried solving for F and i got 219.8 but that is wrong and i think it may have to do with something about not factoring in the μ

_{k}.

Any suggestions?

Thank you

Last edited: