- #1

FaraDazed

- 347

- 2

## Homework Statement

a block of mass 2kg is in at rest on a rough plane inclined at 30°, it is in limiting equilibrium with with a force of 20N applied horizontally (to the ground).

Find the coefficient of static friction between the block and the plane.

## The Attempt at a Solution

[itex]

R=mgcos30+20sin30\\

.\\

mgsin30-μR=20cos30\\

mgsin30-μmgcos30+μ20sin30=20cos30\\

9.8-16.97μ+10μ=17.32\\

9.8-26.97μ=17.32\\

-26.97μ=7.52\\

μ=-0.28\\

[/itex]

Now I now my answer cannot be minus something as 0<μ<1, however, I am unsure as to whether it is my understanding of the question or the algebra I have got wrong. I am sure its a silly mistake, it usually is with me but any help or advice is greatly appreciated.