Question

Two blocks of masses m1 = 4.4 kg and m2 = 4.8 kg are connected by a string as shown in the figure above. Block 1 moves at a constant velocity down the incline 30 degrees) block two is not at incline it is straight. they are attached with a string.

a) Find the coefficient of kinetic friction assuming it is the same for both blocks:

-> I have made acceleration 0 (zero) because velocity is constant, however using the mass of the first block on the incline I tried finding the fk (kinetic fric) then using that I found mk (miu kinetic) ... It didn't work

Please help

Answer 1

If I have this picture right block one on the incline is pulling block two on the level above toward the incline.
There is one force pulling block one down the incline and string tension T holding it back
Fpull = 4.4 g sin 30 = 2.2 g

2.2 g - T = mu * 4.4 g cos 30

I assume that string goes over a frictionless pulley so T pulls forward on bloc 2

T = mu * 4.8 g
so
2.2 g - mu * 4.8 g = mu * 4.4 g * .866

2.2 g = mu g (8.61)

mu = 2.2 / 8.61 = .256