Work done by friction

[DaRotot]

A 2.3-kg block slides down a plane (inclined at 43degrees with the horizontal) at a constant speed of 3.3 m/s. At what rate is the frictional force doing work on the block?

 

[Nylex]

The rate of doing work is just the power. Do you know an expression relating power and velocity? You'll also need the frictional force, but you should be able to get it because you're told that the block is travelling at a constant speed..

 

[Dr.Brain]

..and also the work done will be negative , since the direction of the frictional force is opposite to the displacement direction.

BJ