# Homework Help: Centripetal Motion

1. Oct 20, 2004

### dekoi

Would anyone be kind enough to explain the concept of centripetal (circular) motion to me?

How accelerations are determined (i understand they are non constant);

What factors affect this motion, and/or what factors relate to it.

How do limits relate to this type of acceleration?

Thank you.
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I understand the concept of this sort of acceleration. The speed remains constant throughout the cycles, however, the acceleration changes due tot he change in direction -- and thus a change in velocity.

Howevever, i am not sure how frequency of the cycles affects e.g. tension (of a string, if a string is spinning with an attached rubber stopper for example), how mass affects frequency, and other relationships with frequency.

Last edited by a moderator: Oct 20, 2004
2. Oct 20, 2004

### UrbanXrisis

Sounds like a direct hw question from the text :uhh:

Try giving it a try and I'm sure you can find all the answers on google

3. Oct 20, 2004

### dekoi

It is not a direct homework question. Although I'm glad you feel my sentence structure seems like it :)

I understand the concept of this sort of acceleration. The speed remains constant throughout the cycles, however, the acceleration changes due tot he change in direction -- and thus a change in velocity.

Howevever, i am not sure how frequency of the cycles affects e.g. tension (of a string, if a string is spinning with an attached rubber stopper for example), how mass affects frequency, and other relationships with frequency.

4. Oct 20, 2004

### UrbanXrisis

Circular motion is characterized by an orbital radius r, a speed v, the mass m of the object which moves in a circle, and the magnitude F of the centripetal force. The force of the Centripetal motion equals (m*v^2)/r

velocity=2*pi*R/T
acceleration=v^2/R
angular frequency= 2pi/T

T is the period

Last edited: Oct 20, 2004
5. Oct 23, 2004

### dav2008

That's assuming uniform circular motion where the only acceleration is towards the center of the circle.

In non-uniform circular motion (where the speed of the object is accelerating) there is also a tangental component of acceleration that is tangent to the circle of motion. You can then take the vector product of the tangential and centripital acceleration to get the net acceleration.

6. Oct 23, 2004

### brewnog

Not quite. For your more simple cases, the speed is constant, but the direction is changing, and as a result the velocity is changing, so the object is accelerating.

The acceleration is NOT changing!

For more complex cases (as previously stated by dav2008) you can have a non-uniform acceleration, but I thought this needed clarifying first.