- #1

renob

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## Homework Statement

A 68 kg crate is dragged across a floor by pulling on a rope attached to the crate and inclined 15 degrees above the horizontal.

(a) If the coefficient of static friction is .50, what minimum force magnitude is required from the rope to start the crate moving?

(b) If [tex]\mu[/tex]k=0.35, what is the magnitude of the initial acceleration of the crate?

## Homework Equations

F=ma

## The Attempt at a Solution

part a:

I calculated the weight (9.8)(68 kg)=666N

then I got static friction: (666N)(.50)=333N

I substituted all the forces into Newtons second law and got:

ma=Normal+Gravity+Static+Applied force

after I plugged in the variables I got 0=333N + (force applied)(cosx)

(It's 0 because the box isn't moving so a=0)

when i solve for force i get 344.7N but the answer in the book is 300N