# Circular motion-find the minimum speed

The question is:

A ball of a mass 4kg is attached to the end of a 1.2m long string and whirled around in a circle that describes a vertical plane..what is the minimum speed that the ball can be moving at and still maintain a circular path?

i try solve it by use T+mg=mv*2/r.But i cant find the tension...

nasu
Gold Member
The question is:

A ball of a mass 4kg is attached to the end of a 1.2m long string and whirled around in a circle that describes a vertical plane..what is the minimum speed that the ball can be moving at and still maintain a circular path?

i try solve it by use T+mg=mv*2/r.But i cant find the tension...

You don't need to calculate the tension. What is the condition for the "minimum speed"?
Or what happens with T when v is less than that minimum?

Can you give me the answer...because i still dont understand it..

You don't need to calculate the tension. What is the condition for the "minimum speed"?
Or what happens with T when v is less than that minimum?

Can you give me the answer...because i still dont understand it..