A 100.0-kg rollercoaster cart starts at the top made to roll down the hill so that it picks up speed. The cart must have a speed of 12 m/s at the top of the loop to complete a circular loop of radius R = 8.0 m. It then compresses a massive spring with k=14000 h=? N/m until it comes to a stop. R a. Using conservation of energy, determine the required height h of the hill.) [2 marks] b. Using conservation of energy, determine the compression of the spring [2 marks]. c. How much work would the breaks need to do to slow the coaster to 1/2 the velocity after exiting the loop and before hitting the spring? [2 marks]