A catapult launches a test rocket vertically upward from a well, giving the rocket an initial speed of 79.6 m/s at ground level. The engines then fire, and the rocket accelerates upward at 4.20 m/s2 until it reaches an altitude of 960 m. At that point its engines fail, and the rocket goes into free fall, with an acceleration of ?9.80 m/s2. (You will need to consider the motion while the engine is operating and the free-fall motion separately.)
(a) For what time interval is the rocket in motion above the ground?
s
(b) What is its maximum altitude?
km
(c) What is its velocity just before it hits the ground?
m/s