Question

A particle is moving along $x-$axis. Its $x-$coordinate varies with time as : $x=-20+5t^2$ For the given equation match the following two columns

Answer 1

$x=-20+5t^2$
For $x=0$
$5t^2-20=0$
this gives $t=2s$
$A\to 3$
$\frac{dx}{dt}=5t$
$\frac{d^{2}x}{d{t}^2}=5$
both are equal at $t=1$
$B\to 2$
Particle will change its direction of motion when $v=0$
$\frac{dx}{dt}=0$
this gives $t=0$
therefore, particle does not changes its direction of motion.
$C\to 4$
$D\to 1$