### Q.9:- 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.

**Answer:-**

Mass of the rocket, *m* = 20,000 kg

Initial acceleration, *a* = 5 m/s^{2}

Acceleration due to gravity, *g* = 10 m/s^{2}

Using Newton’s second law of motion, the 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 × 10^{5} N