A roller coaster uses 800 000 J of energy to get to the top of the first hill. During this climb, it gains 500 000 J of potential energy and pauses (velocity = 0) for a fraction of a second at the

very top before heading down the other side.

a) Draw a Sankey diagram for the roller coaster’s climb.

b) What's the kinetic energy at the very top? How do you know?

c) What would be the "useful energy" during its climb to the top? How do you know?

d) How much energy was lost due to friction? (Use Ebefore = Eafter).

e) Calculate the efficiency of the roller coaster during this part of the ride (the climb).