Question

An object travels in a circular path at constant speed. Which statement about the object is correct? A It has changing kinetic energy. B It has changing momentum. C It has constant velocity. D It is not accelerating.

Answer 1

`B`

Explanation:

kinetic energy depends on magnitude of velocity i.e `1/2 mv^2` (where, `m` is its mass and `v` is speed)

Now, if speed remains constant,kinetic energy doesn't change.

As,velocity is a vector quantity,while moving in a circular pathway,though its magnitude is fixed but direction of velocity changes,so velocity doesn't remain constant.

Now,momentum is also a vector quantity,expressed as `m vec v`,so momentum changes as `vec v` changes.

Now,as velocity is not constant,the particle must be accelerating, as `a=(dv)/(dt)`