I need help with Ramp and Pulley Physics Problem

  • Thread starter spg93
  • Start date
  • #1
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Homework Statement



The suspended 2.2 kg mass on the right is
moving up, the 2 kg mass slides down the
ramp, and the suspended 8.9 kg mass on the
left is moving down. There is friction between
the block and the ramp.
The acceleration of gravity is 9.8 m/s2 . The
pulleys are massless and frictionless.
What is the tension in the cord connected
to the 8.9 kg block?
Answer in units of N.

(Diagram with variables: File posted and also at http://s1219.photobucket.com/albums/dd425/spg93/?action=view&current=Physics.jpg)


Homework Equations


Force of Friction= coefficient of friction*Normal Force
Force of Gravity= mass*gravity
Fx=mgcos28
Fy=mgsin28

The Attempt at a Solution



I really have no idea where to start. I drew a force diagram for all three boxes. I also solved for the Forces in X direction and forces in Y direction. I figured the forces in the Y direction would be the normal force, so I divided by the coefficient of friction to try and get force of friction. My answer did not work and I'm completely lost. Any help would be really appreciated.
 

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Answers and Replies

  • #2
IBY
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Firstly, what is the total force on the 8.9kg object? That is the first thing you have to ask because you want to find the tension on that object. Also, because the 8.9 kg object is moving down, that means that total force is down. So, what is the total force? The total force is its weight minus the tension that makes it go up. The reason being that because 8.9kg is going down, its weight must be greater than its tension. Now, the question is, what is tension? Tension is, of course, is all the added force due to 2kg and 2.2kg objects because they are the only one that are pulling back.
 

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