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.

							F=mrw^2F=mv^2/rNow F IS CONSTANTThus,mv^2/r is constantNow r will be constant Thus mv^2 is constantThis implies Kinetic energy I.e. mv^2/2 is also constantHere velocity and acceleration will not be constant since velocity is a vector quantity and in a circular motion velocity will keep changing
						

							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 :c) its kinetic energy is constant
						

							
If a force of constant magnitude which is always perpendicular to the velocity of the particle acts on a particle,the work done and hence the change in kinetic energy will be zero, therefore option (c) Kinetic energy is constant, is the correct option.     
						

							
Dear User
In Uniform circular motion,magnitude of velocity i.e. speed is constant.
Velocity changes as the direction varies at every instant. And yes it moves in a circular path. So kinetic energy is constant. As magnitude remains constant. So the correct options are (c)and(d)