Physics
posted by Mike .
A 2.40 kg mass, m, on a frictionless table is moving in a circle with radius 0.500 m at a constant speed. m is attached to a 5.70 kg mass, M, by a cord through a hole in the table. Find the speed with which m must move for M to stay at rest

I'm in this class too :/
For this problem, you have to use both equations F=Ma and F=(mv^2)/r
Step 1: solve for F using F=Ma
5.70kg x 9.81 m/s^2 = 55.917 N
Step 2: plug this into the other equation
55.917N = (2.40kg x v^2)/0.500m
(55.917N x .5m)/2.40kg
=11.65 m^2/s^2
(squareroot)11.65 = 3.41 m/s
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