Question

A rocket with a lift-off mass of 20,000 kg is blasted upwards with an initial acceleration of \( 5.0 ms^{-2} \). Calculate the initial thrust (force) of the blast.

Answer 1

Given,

Mass of the rocket,\( m = 20000 kg = 2 \times 10^4\ kg \)

Initial acceleration = \( 5 ms^{-2} \)

\( g = 9.8 m/s^2 \)

The initial thrust (force) should give an upward acceleration of \( 5 ms^{-2} \) and should overcome the force of gravity.

Thus the thrust should produce a net acceleration of \( 9.8 + 5.0 = 14.8 ms^{-2}. \)

Using Newton’s second law of motion, the initial thrust acting on the rocket

Thrust = force = mass \times accelerationThrust=force=mass×acceleration

\( F = 20000 \times 14.8 = 2.96 \times 10^5 N \)

The initial thrust force of the blast is \( 2.96 \times 10^5 N \)