# Frictional force, normal force and coefficient of friction

#### lisa1991

1. 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.

2. Homework Equations

Ff= u x Fn
F= m x a

3. 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

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#### 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

Mentor
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 [Broken]

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.

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