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How does one do this question?

by EPFLstudent
Tags: decomposition, friction, mass, mechanics, tension
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Nov20-12, 09:51 AM
P: 2
Figure attached below. You have a big block of mass M and a small block of mass m. When m=3kg, the acceleration of the large block is 0.6ms-2. When m=4kg, the acceleration of the large block is 1.6ms-2. The dynamic friction coefficient between the large block and the surface it slides on is μ. There is no friction between any other surface. Questions:

a) Express the relationship between the movement of block m and block M
b) Derive expressions for the motion of block m and block M.
c) Determine the mass of block M and the dynamic friction coefficient, μ, between it and the surface it slides on.

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Nov20-12, 10:02 AM
P: 953
Nice problem. So what have you got so far? How does the motion of mass m relate to the motion of mass M?
Nov20-12, 10:19 AM
P: 2
I know that [itex] x_m = 2 x_M [/itex], so that the small block moves two times as much as the big block. My problem is decomposing the forces.

Nov20-12, 10:32 AM
Sci Advisor
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P: 6,530
How does one do this question?

Draw free body diagrams. Start with the mass m. What forces are acting on m?

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