I need to sketch a graph of the gravitational potential energy (y axis) of a block as a function of its kinetic energy (x axis).

Question

The block is at the top of an inclined plane. It starts from rest and slides without friction down the length of the incline.

I need help with showing this. I know GPE at the top = KE at the bottom. Do I just draw a 45 degree line from y axis to the x axis?

I don't understand labing the graph with appropriate values and units.
m = 20 kg, h = 5 m, length of inclline = 10 m.

Answer 1

Potential energy = Constant - Kinetic energy

y = C - x

Yes, that will give you a 45 degree line sloped downward

The Constant can be anything, but must stay the same as the block descends. In your case one would probably choose the potential energy to be zero at the bottom of the inclined plane, so C would be the potential energy at the top of the incline.

For your graph, PE = 5*9.8*20 Joules at the top, and KE = 0 there. You don't need to know the length of the incline to draw the graph (when there is no friction).