Question

A model rocket accelerates from rest upwards at $50m/s^2$ for $2s$ before its engine burns out. The rocket then coasts upward. What is the maximum height that the rocket reaches (assume air resistance is negligible)

• A. $100m$
• B. $600m$
• C. $500m$
• D. $1000m$

Answer 1

The correct option is B $600m$

The height reached in the $2sec$ will be $h=\frac{1}{2}\times 50\times 2^2=100meter$

and the velocity $achieved$ in these $2sec$ will be $u=at=50\times 2=100m/s$

After these $2sec$ the engine will get burns out so $no$ more that acceleration and then $gravity$ will come into play.

Now the further height due to this velocity $u$ will be $H=\frac{u^2}{2g}=\frac{10000}{20}=500meter$

so the max height reached will be $h+H=600meter$