A Block Sliding Down an Incline

[PrideofPhilly]

Homework Statement

Starting from rest, a 5 kg block slides 2.5 m down a rough 30 degree incline. The coefficient of kinetic friction between the block and the incline is 0.436. The acceleration of gravity is 9.8 m/s2.

Find the work done by the force of gravity.

Find the work done by the normal force.

Homework Equations

Wgravity = mgh

The Attempt at a Solution

I figured out work done by force of gravity:

Wgravity = (5 kg)(9.8 m/s2)(2.5sin30) = 61.25 J

However, I don't know how to find the work done by the normal force. Is it the same as work done by gravity?

 

[LowlyPion]

There is another force involved - friction.