# Homework Help: Two blocks tied with massless rope sliding down an incline

1. Oct 4, 2011

### sheeproars

1. The problem statement, all variables and given/known data
On 20 degree incline, there are two blocks tied together with a rope, sliding down. the block on the top has mass of 2.0 kg (m1) and u_k1(coefficient of kinetic friction for block 1) = .30 the block on the bottom of the incline has mass of 3.0 kg (m2) and u_k2 = .20
What is the tension of the rope?

2. Relevant equations
F=ma, f = F_N*u

3. The attempt at a solution
I found F_net for each block by F_net = F_gx(Force of gravity in horiz. direction) - f(friction)
and got F1_net = .8236 N and F2_net = 4.1754 N
and because of acceleration constraint, and because block 1 has slower accel, I found accel for block 1, which was .4118 m/s^2 and found F = m2(a) = 1.2354 N
Because F2_net is larger than F = m2(a), I subtracted those two and got T = 2.94 N which is not correct.

2. Oct 4, 2011

### SammyS

Staff Emeritus
Draw a Free Body Diagram for each block.

How did you account for friction?

3. Oct 5, 2011

### sheeproars

I figured it out! I just didn't draw the right free body diagram..

Thanks!