A block of weight w = 20.0N sits on a frictionless inclined plane, which makes an angle θ = 24.0∘ with respect to the horizontal, as shown in the figure. (Figure 1) A force of magnitude F = 8.13N , applied parallel to the incline, is just sufficient to pull the block up the plane at constant speed.

a) What is Wg, the work done on the block by the force of gravity w⃗ as the block moves a distance L = 5.00m up the incline?

Question

A block of weight w = 20.0N sits on a frictionless inclined plane, which makes an angle θ = 24.0∘ with respect to the horizontal, as shown in the figure. (Figure 1) A force of magnitude F = 8.13N , applied parallel to the incline, is just sufficient to pull the block up the plane at constant speed.

a) What is Wg, the work done on the block by the force of gravity w⃗  as the block moves a distance L = 5.00m up the incline?

anonymous · Answer

Gravity only acts perpendicularly to the earth's surface. 

The work done by gravity would be equal to $$W_g = mg y$$where $y$ is the VERTICAL displacement of the block. Or$$y = L \sin(\theta)$$