Work Done on a Block on an Inclined Plane

[gunjay]

Homework Statement

A block of mass m=18kg is pushed horizontally with a force of F_p=150N up an inclined plane of angle θ=32° and coefficient of friction of μ=0.10, a distance of x=5m. a) What is the work done by F_p. b) Work done by the gravitational force. c) Work done by the normal force.

Homework Equations

W = ∫Fdl
Force in the same direction as displacement.
or W = F*x

The Attempt at a Solution

My main question is how is work affected by friction?
This question is like a part 2 where the first one had no friction and this one does but i don't see how friction gets involved at all.

a) The F_p has 2 components, one that moves parallel to the inclined plane and the other perpendicular to the plane. so F_px=F_pcosθ. So including friction do i do W = (F_px-F_f)*x or just W=F_px*x or ?

b) W_g=∫F_gdx = mgsinθ*x

c) W_N=∫F_Ndx = 0 = there is no displacement in the direction of the normal force.

 

[paisiello2]

a) You got it with your second equation there. It's irrelevant whether you are fighting against gravity, friction, or little green men pushing back in the opposite direction. Work is work.

b) and c) You got it. Friction only causes the block to accelerate slower.

 

[gunjay]

I believe i found the answer.
There was a part d that i thought didn't apply but it did. d) asks for the velocity of the block after it moves those 5m. Using KE= net W i was able to find an answer using friction that also seems plausible.