# Chapter 4 - Motion in Two and Three Dimensions - Problems: 61a

126km/s

#### Work Step by Step

The star rotates once every second. If a particle is on the equator, we need to find the distance that it would cover in one revolution (the circumference of the star). This is 2*pi*r where the radius is 20km = 125.6km. Therefore, the speed of the particle is 125.6km in one second or 126km/s

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