A hockey puck of mass m is attached to a string that passes through a hole in the center of a table, as shown. The hockey puck moves in a circle of radius r. Attached to the other end of the chain, and suspended vertically under the table, is a mass M
The tension of the rope must balance the weight of m2 and is therefore equal to T = m2*g.
Centripetal acceleration of the first object:
a = v^2/r
This tension is the ONLY force that provides centripetal acceleration for m1 (all other forces are perpendicular to the circular motion and all add to zero), and is therefore also equal, according to Newton’s second law:
T = m1*v^2/r
Combine with the other equation:
m2*g = m1*v^2/r
Solve for v:
v = sqrt(r*g*m2/m1)
And also provide the voltage as an answer:
T = m2*g