Newton's Third Law/ Circular Motion

AI Thread Summary
To determine the speed at which mass m1 must rotate in a circle of radius r for mass m2 to remain at rest, the tension in the string must equal the weight of m2, leading to T = m2g. The net force on m1 is equal to the tension, resulting in m1a = T, which simplifies to a = m2g / m1. Substituting the centripetal acceleration formula a = v^2 / r allows for the calculation of speed, yielding v = sqrt(r * m2g / m1). The derived formula is confirmed as correct for this scenario.
dekoi
Question:
Mass m1 on the frictionless table is connected by a string through a hole in the table to a hanging mass m2. With what speed must m1 rotate in a circle of radius r if m2 is to remain hanging at rest?

My answer:

Fnetym2 = T - m2g
For m2, a = 0
Therefore,
0 = T - m2g
T = m2g

Fnetxm1 = T
m1a = T
m1a = m2g
Therefore,
a = m2g / m1

Since a = v^2 / r, v = sqrt(ra)

Therefore,
v = sqrt(rm2g / m1)

Is this correct?
 

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Looks correct to me.
 
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