# Finding tension in a rope problem

1. Feb 28, 2010

### mullets1200

1. The problem statement, all variables and given/known data
A 60kg man is climbing a rope that is connected to a pulley and on the other side the rope is connected to a 100kg block. what is the tension in the rope?

2. Relevant equations
T-mg+F=ma

3. The attempt at a solution
this was my attempt:
Mg-T-F=Ma;
I get a=0.4
T+F=60(g+a)
=840N
but the answer is wrong. where did i go wrong??

2. Feb 28, 2010

### shallgren

What's that extra F doing in there? You have two cases: The block and the climber.

Draw free body diagrams. There are two forces acting on both the block and the climber. They will both fight against each other to equal the Net force = m*a. Create a system of equations.

3. Feb 28, 2010

### mullets1200

for the man it is:
T-mg+F=ma
for the block:
Mg-T-F=Ma

is that correct?

4. Feb 28, 2010

### shallgren

Oh I see what you're doing now.

Newton's second law states that $$F_{net} = m \cdot a$$ for the case of a rope problem, the net force IS the combination of tension and weight. Get rid of the extra F in there and you are right.

5. Feb 28, 2010

### mullets1200

ah! got it. thank you so much!