Question

A particle moves along x-axis in such a way its coordinate (x) varies with time (t) according to the expression $x=2-5t+6t^2$. its intial velocity is

• A. $-3m{s}^{-1}$
• B. $-5m{s}^{-1}$
• C. $2m{s}^{-1}$
• D. $3m{s}^{-1}$

Answer 1

The correct option is B $-5m{s}^{-1}$

Given $x=2-5t+6t^2$

and we know $v=\frac{dx}{dt}=-5+12t$

At initial position time will be 0 thus its initial velocity $u=-5+12\left(0\right)=-5m/s$