A body moving with constant speed in a circle has

  • A. constant velocity
  • B. zero acceleration
  • C. changing velocity and therefore acceleration
  • D. no force acting on it

Explanation

Velocity is a vector, so a continuous change of direction is a change of velocity even at constant speed, and the acceleration points towards the centre. A net force must therefore act, supplied by tension, friction or gravity depending on the situation. Constant speed and constant velocity are not the same thing.

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