A rocket with a lift off mass 20000 kg is blasted upwards with a net initial acceleration of `5 ms^(-2)` Calculate the initial thrust (force) of the blast.

Explanation

Here , m = 20000 kg = `2.0 xx 10^(4)` kg
initial acceleration = `5 ms^(-2)`
Clearly, the thrust should be such that it overcome the force of gravity besides giving it an upward acceleration of `5 ms^(-2)`
Thus the force should produce a net acceleration of 9.8 + 5.0 = 14.8 `ms^(-2)` . Since, thrust = force mass `xx` acceleration
f = `2.0 xx 10^(4) xx 14.8 ` = ` 2.96 xx 10^(5)` N .