How does gravity and friction affect work on a slanted surface?

[Feyre]

Work, friction and gravity

Homework Statement

Calculate the work done on the slanted portion by gravity and friction

Homework Equations

The Attempt at a Solution

Work is Fdx

F:
Gravity is $L\sin\left(\theta\right)mg$
Friction is $L\cos\left(\theta\right)mg\mu_{1}$

dx:
Friction travels along a path L, but is this also true for gravity?

Simply squaring the L's and adding them together, or subtracting friction, registers as incorrect.

 

[lendav_rott]

You already calculated the work done by gravity and friction. as you said
Gravity is Lsin(θ)mg
Friction is Lcos(θ)mgμ1

Friction doesn't travel, friction is a phenomenon caused by gravity, gravity always acts "straight down". The vector of the force of friction is parallel to the ramp's surface, yes. mg sin(a) is the ramp directional component of the force of gravity (imagine it as an invisible rope being pulled by invisible somebody).

assuming L is the distance the block travels down the ramp, then the above are the work done by the respective forces.

If you wanted to find out the total energy spent in this process, then you would have to add them together, don't create energy out of nothing, though.

 

[Feyre]

Not sure why I rambled about squaring the L's.
There was a problem with the website, I hate those digital things.
Thanks anyway.