Applications Of Derivatives Question 374

Question: The equations of motion of two stones thrown vertically upwards simultaneously are $ s=19.6,t-4.9,t^{2} $ and $ s=9.8,t-4.9,t^{2} $ respectively and the maximum height attained by the first one is h. When the height of the first stone is maximum, the height of the second stone will be

Options:

A) h/3

B) 2h

C) h

D) 0

Show Answer

Answer:

Correct Answer: D

Solution:

The time taken by first stone to secure maximum height = $ t=\frac{u}{g}=\frac{19.6}{9.8}=2sec $ .

The time taken by second stone to secure maximum height is, $ t=\frac{9.8}{9.8}= $ 1sec. Therefore, in 2 sec, second stone will come back to the ground.

Hence height $ s=at^{2}+bt+6 $ .