Question

A particle is moving along straight line (x axis) & position of particle is given by $x=t^2-7t+12$, then at $t=3.2$, the speed of particle will

• A. increase
• B. decrease
• C. become zero
• D. increase or decrease

Answer 1

The correct option is B decrease

$x=t^2-7t+12$
$\begin{array}{c}v=2t-7\\ a=2\end{array}\}att=3.2$
$v=2\times 3.2-7=-0.6$
$a=2$

As the velocity and acceleration directions are opposite, we can say that speed is decreasing.