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## Homework Statement

A ball is going around in a circle of radius 5 m.

It starts from rest, and goes through an angle change of 26 rad in 5 seconds.

The ball weighs 0.3 kg.

Find its moment of inertia, and find the torque about the origin.

## Homework Equations

## The Attempt at a Solution

What I'm doing seems too simple, so I bet it's wrong...

I thought moment of inertia was just mass times radius

^{2}. My textbook doesn't give it for this situation but it gives the moment of inertia for other shapes, all of which are this but multiplied by some factor.

And I think the torque would be zero because the force acting on the ball would be towards the center of the circle, and since torque is r x F, and F is 180 to r, rFsin(180) = 0.