Question

let’s assume that we have a block sliding down a straight plane, instead, as shown to the right. It slides from the top to the bottom.

2-1.Does the amount of work that gravity does depend on whether or not there is friction between the block and the plane? Explain.

2-2. If there is friction, does the amount of work that friction does depend on only the vertical displacement, or does it also depend on the horizontal displacement? Why?

Answer 1

amount of work that gravity => m*g * ( change in height w.r.t the refrence point )

so work done by gravity doesn't depend of  friction

work done by friciotn = fricion force * displacement *cos( theta)

here dispalcemnt should be in the anti parallel direction to the friction force

so it doesn't matter  whether it  is vertical or horizontal you alwyas need to consider the displacement  anti parallel to the fricional force ( anti parallel becuase friciton always act in opposite direction of movement )

i hope this helps if not plz let me know in comment i will be happy to help.