# Is this correct? Newton's second law related.

1. Feb 17, 2013

### Questions999

On an object with a mass of 3 kg a single force F acts perpendicular to the speed of the object.The object moves in a circle with a radius of 2 meters and the period is 3 seconds.a) Find the acceleration. I have the formula T=2*pi*r/v ,I find v here and then in the formula a=v^2/2 I replace v.
b) Find the module of the force F.
I think that it is F=m*v^2/r - mg and I have all the data to find F.

2. Feb 17, 2013

### lep11

Correct.

Incorrect.

3. Feb 17, 2013

### Questions999

what is exaclty incorrect ? :)

oh is it 0?the force?

Last edited: Feb 17, 2013
4. Feb 17, 2013

### lep11

If the object is rotated at the end of a rope in a circular path, then the force acting on it is the tension of the rope. For example if a car is driving circular track then the force is friction.

5. Feb 17, 2013

### Questions999

so now I have T*cosx=mg ..and I find T :) Thanks :D

6. Feb 17, 2013

### lep11

Nope. Then it wouldn't be in circular motion at all.

7. Feb 17, 2013

### lep11

Am I missing something here? What is module of a force? The force is simply F=m*v^2/r