Question

20-50. A 1200-lb rocket is fired vertically upward. The rocket motor develops a constant thrust of 2200 lb. What is the velocity in mph of the rocket when it is 1 mile above its starting point? Neglect the decrease in the weight of the rocket because of fuel expenditure.

Answer 1

We know that

Comment: Thrust in lb is equivalent to F*g in lbm.ft/s^2 where g is acceleration due to gravity = 32.174 ft/s^2.

As the rocket is moving vertically upwards, earth's gravity will reduce effective acceleration.

Converting to miles/hr^2; 1 ft/s^2 = 2454.54 miles/hr^2

We have equation of motion