Kinematics Question 400
Question: A rocket it’s fired upward from the earth’s surface such that it creates an acceleration of $ 19.6m{{s}^{-2}} $ . If after 5 s, it’s engine it’s switched off, the maximum height of the rocket from earth’s surface would be
Options:
A) 980 m
B) 735 m
C) 490 m
D) 245 m
Show Answer
Answer:
Correct Answer: B
Solution:
Velocity when the engine it’s switched off $ v=19.6\times 5=98\text{ m}{{s}^{-1}}\text{ }{{h} _{\max }}=h _{1}+{h _{{}}} $ Where $ {{h} _{1}}\text{=}\frac{1}{2}a{{t}^{2}}\text{, }{{h} _{2}}\text{=}\frac{{{v}^{2}}}{2a} $
$ {h _{\max }}=\frac{1}{2}\times 19.6\times 5\times 5+\frac{98\times 98}{2\times 9.8}=73.5\text{ m} $
