Question

A rocket travel vertically upward with velocity 20m/s after 35 sec fuel supply is cutoff and travels like a free body the height acheived by it is

Answer 1

Velocity of the rocket (u) = 20 m/s

It travels at constant speed for 35 seconds.

Hence, distance covered in 35 s = Speed × time

Distance = 35 × 20 = 700 m

Now, the rockets fuel is cut off.

Initial speed (u) = 20 m/s

Final speed (v) = 0 m/s

a = -9.8 m/s^2

Let the height covered further be H.

Using third equation of motion:

$v^2 = u^2 + 2aH$

$0^2 = 20^2 - 2 \times 9.8 \times H$

$H = \frac{400}{19.6}$

H = 20.4 m

Total Height achieved = (700 + 20.4 ) m

Height = 720.4 m