- #1

Waelroe

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## Homework Statement

A box is placed on an angeled surface.

m = 15 kg

f = 0,3

[PLAIN]http://img5.imageshack.us/img5/8717/friction.png

Will the box slip downwards if X = 0?

How big does the force X have to be to push th box upwards?

## Homework Equations

## The Attempt at a Solution

My idea was that the only force working upwards is Ff.

A = 55°

g = 9,81

N = mg*cos(90-35)+18 = 102,40 N

Ff = 0,3*N = 30,72

Force downwards: mgcos35-18 = 102,54 N

The force down is greater than Ff therefore it would slip if X = 0.To get how big X needs to be to make the box move up i simply subtracted the force down with Ff and got = 71,82 N.Could this possibly be correct?

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