A rocket with a lift-off mass $2\times {10}^{4}kg$ is blasted upwards with an initial acceleration of $5m{s}^{-2}$. The initial thrust of the blast is (Take $g=10m{s}^{-2}$)

Here, $m=2\times {10}^{4}kg$

Initial acceleration, $a=5m{s}^{-2}$

Initial thrust $=$upthrust required to impart acceleration $a$+upthrust required to overcome gravitational pull

$F=m\left(a+g\right)=\left(2\times {10}^{4}kg\right)\left(5+10\right)m{s}^{-2}=3\times {10}^{5}N$