You are in charge of testing or designing a new amusement park ride. At the end of the ride, the 1200 kilogram cart (including people) goes down a hill that is angled at 30 degree from the horizontal. The starting height of the cart is 20 meter above the ground, and it is going 5 meter per second at the top of the hill. There is a constant force of friction of 30 Newton on the cart the entire ride. At the bottom of the hill, the cart travels 50 meter before being stopped by a spring that is compressed by 2 meter. Evaluate the spring constant of the spring?