Question

In the figure we see a mass m2=0.2 kg undergoing circular motion of radius 0.5 m on a frictionless table. The second mass, m1=0.3 kg, is attached to m2 with a string and hangs down below the tabletop. How fast does m2 have to be moving so that m1 remains stationary?

In the figure we see a mass m2=0.2 kg undergoing circular motion of radius 0.5 m on a frictionless table. The second mass, m1=0.3 kg, is attached to m2 with a string and hangs down below the tabletop. How fast does m2 have to be moving so that m1 remains stationary?

Answer 1

Here ,

for m1 to be stationary ,

the tension in the string T is

T = m1 * g

T = 0.3 * 9.8

T =2.94 N

Now, for mass m2

T = m2*v^2/r

2.94 = 0.2 * v^2/.5

v = 2.71 m/s

the mass m2 must be moving at 2.71 m/s