A rocket is fired vertically up from the ground with a resultant vertical acceleration of $10 \mathrm{m}/{\mathrm{s}}^2$. The fuel is finished in $1 \min$ and it continues to move up. After how much time from then will the maximum height be reached?

$v=10\times 60=600 \mathrm{m}/\mathrm{s} ---\left(\mathrm{i}\right)$

As after burning of fuel the initial velocity from Eq. (i) is  $600 \mathrm{m}/\mathrm{s}$ and gravity opposes the motion of rocket, so the time taken by it to reach the maximum height (for which $v=0$ ).
$$\begin{gathered} 0=600-gt \\ t=60 \mathrm{s} \end{gathered}$$
i.e. after finishing fuel the rocket further goes up for $60 \mathrm{s}$, or $1 \min$.