1: A 4.2 10 kg subway train is brought to a stop from a speed of 0.75 m/s in 0.33 m by a large spring bumper at the end of its track What is the force constant k of the spring in N/m? 2 A rock is thrown from a bridge 19.5 m above water with an initial speed of 14 m/s. Assuming negligible air resistance, what is the speed that the rock hits the water with, in meters per second? 3 A basketball player throws a basketball m = 1 kg straight up with an initial speed of vo = 6.5 m/s. The ball leaves his hand at shoulder height ho = 2.05 m. Let gravitational potential energy be zero at ground level. Part (a) Give the total mechanical energy of the ball E in terms of maximum height hm it reaches, the mass m, and the gravitational acceleration g. Part (b) What is the height, hm in meters