# Centripetal force on table.

1. Oct 17, 2009

### cruisx

1. The problem statement, all variables and given/known data
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 [Broken]

2. Relevant equations

m(v2/R

v = 2piR/T

T = 1/f

ac = 4pi * R/ T2
3. The attempt at a solution

Well i dont 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 dont 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.

Last edited by a moderator: May 4, 2017
2. Oct 17, 2009

### 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.