# Two blocks hanging

1. Sep 21, 2010

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

A block is hanging from a rope which has another rope connected to another block underneath.
The top block has a mass of 60 Kg and the bottom block has a mass of 30 Kg. Both blocks are accelerated 1.2 m/s^2 upward. What is the tension force between the two blocks? (Assume rope is mass-less)

2. Relevant equations
F = ma

3. The attempt at a solution

I figured I could get the tension force of the top rope by combining both masses together.

F = ma = (90 Kg)(1.2 m/s^2) = 108 N
F = T - mg; => T = F + mg = 108N - (90 Kg)(9.80 m/s)
T = 990 N

I don't even know where to begin to find the tension force between the two blocks.

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2. Sep 21, 2010

### rl.bhat

When the blocks are accelerating upward, the net acceleration is (a + g).
So F = (m1+m2)(a + g). And for m1
F - T = m1*a

Now find T.

3. Sep 22, 2010

### fizzynoob

Sum of the forces in the why conclude:

Fy = T - (m1+mg)g = (m1+m2)a; T is uniform through out the system

therefor T = (m1+m2)(a+g)