# Blocks are connected by thin strings with tensions

1. Jul 5, 2009

### NikkiNik

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

Four blocks are on a horizontal surface.
<---F2---B---Tx---A---Tz---D----Ty--C---F1-->

The blocks are connected by thin strings with tensions Tx, Ty, Tz. The masses of the blocks are A=41.0 kg, B=21.0 kg, C=29.0 kg, D=39.0 kg. Two forces, F1=47.0N and F2=71.0N act on the masses as shown. Assume that the friction between the masses and the surface is negligible and calculate the tension Tz.

2. Relevant equations

F=ma

3. The attempt at a solution

I calculated the total mass =130 kg
Total force 71-47= 24 N
Then the acceleration F/m=0.1846 m/s^2
Next I calculated the Tension in Tz by :
Tz -F1 = 130 * 0.1846
I got 70.9 N

I'm not sure if that's correct??

2. Jul 5, 2009

### LowlyPion

Re: Tension

Not quite. You have the acceleration of the system. That's a start.

Now you need to figure the internal forces, you know like block 1 times acceleration is presenting a force, block 2 times acceleration ... etc. Then you can determine the tension in the middle cord.

3. Jul 5, 2009

### rl.bhat

Re: Tension

Tz -F1 = 130 * 0.1846 It is not correct.
From Ty -F1 = 29 * 0.1846 find Ty
From Tz - Ty = 39 * 0.1846 Find Tz