10. 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). wn e) Calculate the efficiency of the roller coaster during this part of the ride (the climb). iter 11. The roller coaster goes over the top of the first hill and heads downwards. The roller coaster heads down and levels out as it hits the original level. a) Since they are back at the original level, what do we know about the potential energy at this point? Why? b) If we know that we lost 200 000J to heat energy, what is the kinetic energy at the bottom? (Use Ebefore = Eafter) more c) What is the efficiency of the roller coaster during this part of the ride