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The two identical pucks in the figure rotate together on a frictionless, horizon

ID: 2138466 • Letter: T

Question

The two identical pucks in the figure rotate together on a frictionless, horizontal table. They are tied together by strings 1 and 2, each of length l.


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A)

If their common angular speed is ?, what is the tensions in the first string?

Express your answer in terms of the variables m, ?, and l.


B)

If their common angular speed is ?, what is the tensions in the second string?

Express your answer in terms of the variables m, ?, and l.

The two identical pucks in the figure rotate together on a frictionless, horizontal table. They are tied together by strings 1 and 2, each of length l. If their common angular speed is ?, what is the tensions in the first string? Express your answer in terms of the variables m, ?, and l. If their common angular speed is ?, what is the tensions in the second string? Express your answer in terms of the variables m, ?, and l.

Explanation / Answer

variables L, m, and ?, where m is identical mass of each puck and ? is the common angular speed

The force needed to cause circular motion is F = m ?^2 r
For puck 1, r = L. For puck 2, r = 2L

The only force on puck 2 is the tension in string 2 (call it T2).
T2 = 2 m ?^2 L

The forces on puck 1 are T2 and the tension in string 1 (call it T1), in opposite directions.
T1 - T2 = m ?^2 L
T1 = 3 m ?^2 L