Question

A rocket with a lift-off mass $20000kg$ is blasted upwards with an initial acceleration of $5.0m/s^2$. Calculate the initial thrust (force) of the blast.

• A. $3\times 10^{5}N$
• B. $2\times 10^{5}N$
• C. $4\times 10^{5}N$
• D. $5\times 10^{5}N$

Answer 1

Answer: (A)

Mass of rocket, $m=20,000kg$
Initial acceleration, $a=5m/s^2$
$<br/>g=10m/s^2<br/>$
Using Newton's second law of motion, the net force (thrust) acting on the rocket is given as:
$<br/>\begin{array}{l}<br/>F=mg+ma=m(a+g)=20000(10+5)=20000\times 15=3\times 10^{5}N\\ <br/>F=3\times 10^{5}N<br/>\end{array}<br/>$