# Rotational Motion of an object

1. Nov 6, 2007

### todd.debacker

I have two problems I am working on, and I have no idea about either

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

1. A 0.400-kg object is swung in a circular path and in a vertical plane on a 0.500-m-length string. If the angular speed at the bottom is 8.00rad/s, what is the tension in the string when the object is at the bottom of the circle?

2. At what angle (relative to the horizontal) should a curve 52 m in radius be banked if no friction is required to prevent the car from slipping when traveling at 12 m/s? (g-9.8m/s^2)

2. Relevant equations

1 . m(v^2/r)=T ??

2. ?

3. The attempt at a solution

?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

2. Nov 6, 2007

### hotcommodity

Well, for the first problem, you'll need to relate the objects tangential speed to its angular speed. Any idea on what equation you should use? (Hint: We're dealing with circular motion).

3. Nov 6, 2007

### todd.debacker

I have been attempting to use Vt=rw and then plugging that number into m(v^2/r) to give me the total force

Is the tension the only force?

4. Nov 6, 2007

### hotcommodity

The tension is not the only force, but it's the only force we're concerned with. If you mean "Vt" to be the tangential velocity, that's the correct equation.