How Is Frictional Force Doing Work on a Sliding Block?

[c4iscool]

Homework Statement

A 1.6-kg block slides down a plane (inclined at 25° with the horizontal) at a constant speed of 2.0 m/s. At what rate is the frictional force doing work on the block?

Homework Equations

The Attempt at a Solution

I think that you have to find the potential energy, kinetic energy, 1/2mv^2 , and the force acting on the block, f =m* g. then subtracting the potential from the kinetic and force and this should give me the frictional force acting on the block, right?

 

[rock.freak667]

well you have no information to find the potential energy, so you'll need to consider forces.

If it moves at a constant speed of 2.0 m/s what does this imply about the resultant force on it? (Newton's First law can aid you here)

When you know this, just consider all the forces parallel to the plane.