A roller coaster moving with an initial kinetic energy of 1500 J goes down a hill and through a loop-the-loop as shown. The roller coaster then moves along a level track and stops by compressing a spring with spring constant k = 25000 N/m. The mass of the roller coaster is 1500 kg, the height of the hill is h = 45 m, and the loop has radius r = 10 m. You can neglect the effects of friction on the roller coaster. Consider a system consisting of the roller coaster, earth, and spring. A. What is the change in gravitational potential energy of the system, from when it starts at the top of the hill to when it is at the top of the loop? B. What is the velocity of the roller coaster when it is at the top of the loop? C. The spring at the end of the track eventually stops the roller coaster, and the spring get compressed an amount |ALI. Determine this compression in the spring.