Answer:
velocity of rocket at the time of impact is 48.28 m/s
Explanation:
given,
rise of the rocket = 78 m
Velocity acquires by the rocket = 40 m/s
final velocity = 0 m/s
v = u + gt
0 = 40 - 9.81 × t
t = 4.08 s
now, calculation of displacement
[tex]s = u t + \dfrac{1}{2}gt^2[/tex]
[tex]s = 30\times 4.08 - \dfrac{1}{2}\times 9.81\times 4.08^2[/tex]
= 40.8 m
total height = 40.8 + 78 = 118.8 m
velocity = [tex]\sqrt{2gh} = \sqrt{2\times 9.81\times 118.8 }[/tex]
v = 48.28 m/s
velocity of rocket at the time of impact is 48.28 m/s