Question

A rocket is ejecting $50$ g of gases per second at a velocity of $400$ m/s. The accelerating force on the rocket will be

• A. $22$ dyne
• B. $20$ N
• C. $30$ N
• D. $100$ N

Answer 1

The correct option is B $20$ N

\ inGiven : Velocity of gas ejected, $v=400$ $m/s$

Rate at which the gas is ejected, $\frac{changeinmass}{time}=50$ $g/s=0.05$ $kg/s$

The force acting on rocket, $F=\frac{\Delta p}{time}=v\frac{Changeinmass}{time}$

$\therefore$ $F=400\times 0.05=20$ $N$