# Tensions with 3 blocks on a single pulley

1. Sep 22, 2015

### PAstudent

1. The problem statement, all variables and given/known data

The diagram shows two blocks, each of mass m, connected by cord A, and the top block of mass m connected to the block of mass M by cord B. Both cords are of negligible mass. Cord B passes over a frictionless peg that is fixed in place. The system of blocks and cords is released from rest from the position shown, and because 2m<M, block M descends under constant acceleration the distance h in a time T. Derive, in terms of m, M, h, T, and the acceleration due of gravity g, expressions for the tensions in the cords A and B during that time T

2. Relevant equations

3. The attempt at a solution
The picture shows my work. And I was wondering if I drew the FBD correctly and my equations were correct

2. Sep 23, 2015

### Staff: Mentor

(1) In your FBD for mass 2, you left out the tension from the cord below it.
(2) When writing your equations, take care to use a consistent sign convention for the acceleration.

3. Sep 23, 2015

### PAstudent

So tension A= m(a+g)
And
Tension B= M(g-a)

4. Sep 23, 2015

### Staff: Mentor

Those are correct.