Question

an object of mass M moves with constant speed in circular path of radius R M at the action of force of constant magnitude of the kinetic energy of object is

Answer 1

The mass m is moving in a circular path with a constant speed 
let us say the speed be v m/s

So, owing to its motion in a circular path , the force F acting on the mass is providing it the required centripetal acceleration

So, 

F = mv^2/R

So, 

v= √ FR/m

Hence the kinetic energy of the mass = mv^2/2

or,

KE = m(√ FR/m )^2/2  

=m(FR/m)^2 

= FR/2