Q. A particle moves along $x -$axis in such a way that its coordinate $(x)$ varies with time $t$ according to the expression $x = 2 - 5t + 6t^{2}m,$ the initial velocity of the particle is
A) $3\ {ms}^{- 1}$
B) $6\ {ms}^{- 1}$
C) $- 3\ {ms}^{- 1}$
D) $- 5\ {ms}^{- 1}$
Explanation
(d) Given, $\ \ \ \ \ \ \ \ \ \ \ \ \ x = 2 - 5t + 6t^{2}\ \ \ \ \ \ \ \ \ \ \ \ \ \ldots(i)$
Differentiating with respect to $t$
$\ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \ \frac{dx}{dt} = - 5 + 12t$
At $t = 0\ s,\frac{dx}{dt} = - 5\ {ms}^{- 1}$
Hence, initial velocity $v = - 5\ {ms}^{- 1}$
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.