Question

A particle is acted upon by a force of constant magnitude which is always perpendicular to the velocity of the particle. The motion of the particle takes place in a plane. It follows that:

• A. its velocity is constant
• B. its acceleration is constant
• C. its kinetic energy is constant
• D. it moves in a circular path

Answer 1

Answer: (C), (D)

The correct options are
C its kinetic energy is constant
D it moves in a circular path

When the force is perpendicular to the velocity and constant in magnitude, then the force acts as a centripetal force, and the body moves in a circular path. The force is constant in magnitude, this changes direction of the velocity, but not magnitude and hence kinetic energy will remain constant.
Note: The velocity changes continuously due to change in the direction. The acceleration also changes continuously due to change in direction of force