Question
A rocket with a lift-off mass 20,000 kg is blasted upwards with an initial acceleration of 5.0 m s–2. Calculate the initial thrust (force) of the blast.
Solution
Mass of the rocket, m = 20,000 kg
Initial acceleration, a = 5 m/s2Acceleration due to gravity, g = 10 m/s2
Using Newton’s second law of motion,
Net force (thrust) acting on the rocket is given by the relation,
F – mg = ma
F = m (g + a)
= 20000 × (10 + 5)
= 20000 × 15
= 3 × 105 N
