4. A skyrocket firework burns fuel as it climbs. Its mass, m(h) kg, at height hm is given by 0.065 1+h m(h) = 0.96 + (a) What is the mass of the rocket at h = 0 just before launch? (b) Show the mass of the rocket decreases as the rocket climbs. (c) How much work is required to lift the rocket 10 m if the rocket's mass did not decrease? (d) Approximate the work done as the rock goes from height h to h + Ah. (e) The rocket explodes at a height h = 250 m. Find the total work done by the rocket from its launch to its explosion.