Dynamic motion involving pulleys and friction.

AI Thread Summary
The discussion revolves around solving a dynamics problem involving pulleys and friction. The initial attempt at calculating the mass (mC) resulted in an incorrect value of 1.8. The user then established a relationship between the forces, leading to the equation FfB = MC(9.8 - aA), but faced the challenge of having one equation with two unknowns. A suggestion was made to apply Newton's second law (F = ma) for the other masses involved to derive a second equation. The conversation emphasizes the need for additional equations to solve the problem accurately.
DaftCrunk
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Homework Statement


http://img689.imageshack.us/img689/2315/dynamicsproblem.jpg"

Homework Equations




The Attempt at a Solution



FC = FfB
mC * 9.81 = (6.0)(9.81)(0.30)
mC = 1.8 <---- :(

Obviously that was wrong haha. I then tried to figure out how the pulley affects the relationships of the forces, and figured:

FfB = MC(9.8-aA)
17.6 = MC(9.8-aA) <-----One equation, two unknowns. Need another equation, assuming this one is correct.
 
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Welcome to PF!

Hi DaftCrunk! Welcome to PF! :smile:
DaftCrunk said:
… Need another equation, assuming this one is correct.

Yup! … try F = ma for A-and-B. :wink:
 

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