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Finding tension in a rope problem

  • #1

Homework Statement


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?

Homework Equations


T-mg+F=ma

The Attempt at a Solution


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

Answers and Replies

  • #2
44
0
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
for the man it is:
T-mg+F=ma
for the block:
Mg-T-F=Ma

is that correct?
 
  • #4
44
0
Oh I see what you're doing now.

Newton's second law states that [tex]F_{net} = m \cdot a[/tex] 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
ah! got it. thank you so much!
 

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