If reaction is R and coefficient of friction is, what is work done against friction in moving a body by distance d?

a)

b)

c)

d)

(c)

As shown a block of mass is lying over rough horizontal surface. Let  be the coeeficient of kinetic friction between the two surfaces in contact. The force Of friction between the block and horizontal surface is given by

         (

To move the block without acceleration, the force (P)required will be just equal to the force of friction , ie ,

If d is the distance moved , then work done is given by