Question

imagine a block sliding down a frictionless incline plane.
a. How would the mechanical energy change if the friction force was higher?
b. How would the gravitational potential energy at the end change if the friction force was higher?

Answer 1

First question is(no) there
https://answers.yahoo.com/question/index?qid=20090325081524AAkcZlC
no as = wh

Answer 2

If you have no friction on the incline then you're object will move at a constant motion throughout the incline because there is no opposing motion against it but if you add friction then that will constantly oppose the motion until the object stops so with that information you can now answer the questions because you know how friction affects the speed (velocity) of the object.
Hint:
KE = (1/2)(mass)(velocity)^2
PE = (mass)(gravity)(height)
Those will help you answer your question.

Answer 3

@Johnbc @lolo123

Your answer is not correct.

If the plane is frictionless then the block will move with constant ACCELERATION.

(I assume you meant constant velocity in your answer " object will move at a constant motion")

This is because the component of the weight acting along the plane is constant and has no opposing forces.

When it reaches the bottom its KE will be equal to the loss in PE

IF there is friction then some of the PE is used to overcome the friction force, so the KE will be LESS at the end of the plane.

The loss of height as it slides down the plane is still the same if there is friction, so the change in PE will be the same.