# Moment of inertia, when a velocity of ball triples?

1. Jun 5, 2007

### rcmango

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

What happens to the moment of inertia when the velocity of a ball triples?

2. Relevant equations

3. The attempt at a solution

does the moment of inertia triple? become nin times bigger, remain the same, or become only 1/3 of what it was?

not sure, what is really going on with the inertia in this situation.

2. Jun 5, 2007

### cepheid

Staff Emeritus
The first question I would ask myself is:

What does the moment of inertia depend upon? Does it depend on the velocity?

Do you know what moment of inertia is and how it is defined? Do you know the formula for the moment of inertia of a solid sphere (or how to calculate it)? If so, you should be able to answer this question yourself.

3. Jun 6, 2007

### rcmango

okay, so i assumed that the inertia will stay the same because the radius and the mass are in the formula only.

4. Jun 6, 2007

### ice109

you are correct , though i think at relativistic speeds you get a mass dilation but i don't know jack about that