The work done by a centripetal force

If reaction is $R$ and coefficient of friction ${\mu }_r$ what is the work done against friction in moving a body by distance $d$ ?

The diagram shows a barrel of weight $1.0\times {10}^3 \mathrm{N}$ on a frictionless slope inclined at $30°$ to the horizontal.

The force is parallel to the slope. Whet is the work done in moving the barrel a distance of $5.0 \mathrm{m}$ up the slope?

A lawn roller has been pushed through a distance of $80 \mathrm{m}$ by applying a force of $50 \mathrm{kg}.$wt in a direction inclined at $60°$ with the ground. Calculate the work done on the roller.

Assertion $\left(A\right)$ : The work done by the electrostatic force is zero when a point charge moves in a circular path around another charge.

Reason $\left(R\right)$ : The dot product of force and displacement vectors gives work done.