Frictional force, normal force and coefficient of friction

[lisa1991]

Homework Statement

Calculate the frictional force, normal force and coefficient of friction for an 0.2kg object that is lying on a 35 degree incline.

Homework Equations

Ff= u x Fn
F= m x a

The Attempt at a Solution

I managed to get FN= m x a x cos# = -9.81 x 0.2 x cos35 = 1.61 N

I have no idea how to get Ff, but when I work that out I will be able to work out coefficient (u). Thanks for any help

 

[tms]

Since the block is not accelerating, the net force must be zero. Look at all the forces, and find their components along the incline and normal to it.

 

[lisa1991]

sorry also should have mentioned that 35 degrees is the angle the object starts to move down the slope

 

[NascentOxygen]

sorry also should have mentioned that 35 degrees is the angle the object starts to move down the slope

Hi lisa1991! http://img96.imageshack.us/img96/5725/red5e5etimes5e5e45e5e25.gif

At 35° the component of gravity overcomes friction, so the forces are equal and opposite. Draw a diagram showing the incline and the direction of the forces involved.