Applications Of Derivatives Question 278
Question: The equation of motion of a stone thrown vertically upward from the surface of a planet is given by $ s=10t-3t^{2} $ , and the units of s and t are cm and sec respectively. The stone will return to the surface of the planet after
Options:
A) $ \frac{10}{3}\sec $
B) $ \frac{5}{3}\sec $
C) $ \frac{20}{3}\sec $
D) $ \frac{5}{6}\sec $
Show Answer
Answer:
Correct Answer: A
Solution:
$ \frac{ds}{dt}=10-6t=v $
But $ v=0 $ (at maximum height),
$ \therefore t=\frac{10}{6} $
Therefore, the stone will return in $ 2\times \frac{10}{6}=\frac{10}{3}\sec . $
BETA
