Two points lie on a rotating disc, one twice as far from the axis as the other. Compared with the inner point, the outer point has
- A. twice the angular speed and the same linear speed
- B. the same angular speed and twice the linear speed
- C. half the angular speed
- D. the same linear speed
Explanation
Every point on a rigid rotating body sweeps the same angle in the same time, so the angular speed is common to all of them. Linear speed is r omega, so doubling the radius doubles the speed along the arc. This is why the rim of a grinding wheel moves so much faster than a point near its centre.
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