How Do You Calculate the Frequency for a Mass to Orbit on a Frictionless Table?

[cruisx]

Homework Statement

hi guys i need help solvign the following problem.

A mass 1kg on a frictionless table is attached to a hanging mass 4kg by a cord through a hole in the table. Find the frequency with which 1KG mass must move for 4kg to stay at rest, if the radius of the circle is 75m.



http://img32.imageshack.us/img32/9601/phyp.jpg

Homework Equations

m(v²/R

v = 2piR/T

T = 1/f

ac = 4pi * R/ T²

The Attempt at a Solution

Well i don't really know where to start as there is no angle given so i found the circumference first. which is 4.71 or 471 cm.

I think that is useless because i don't know what to do with it. I know i need to find ac first before i can find the frequency right?

So can someone give me a hit on the first step or where to start?

thanks.

 

[ideasrule]

This is more of a force problem than a harmonic motion problem. Try writing out Newton's second law for both the 1 kg mass and the 4 kg mass. Remember that for an object moving in a circle at speed v, acceleration=v^2/r. Also note that the tension in any massless rope is constant throughout the rope.