How Do You Calculate the Coefficient of Kinetic Friction on an Inclined Plane?

[Fire Slayer]

Homework Statement

Blocks 1 and 2 of masses m1 and m2, respectively, are connected by a light string. These blocks are further connected to a block of mass M by another light string that passes over a pulley of negligible mass and friction. Blocks 1 and 2 move with a constant velocity v down the inclined plane, which makes an angle $$\theta$$ with the horizontal. The kinetic frictional force on block 1 is f and that on block 2 is 2f.

determine the coefficient of kinetic friction between the inclined plane and block 1.

and

Determine the value of the suspend mass M that allows the two blocks to move with constant velocity down the plane

Homework Equations

(sum of forces) = (mass)(acceleration)
(kinetic friction force)=(kinetic friction coefficient)(normal force)

The Attempt at a Solution

I set the sum of the forces equal to zero for both the vertical and the horizontal components, but I don't think they came out right.

 

[cristo]

Why don't you post what you got, and someone can check your work for you.