Question

The position of a particle moving x-axis is given by $x=10t-2t^2$. Then the time (t) at which it will momently come to rest is :

• A. $0$
• B. $2.5s$
• C. $5s$
• D. $10s$

Answer 1

The correct option is B $2.5s$

Displacement, $x=10t-2t^2$

velocity, $\frac{dx}{dt}=10-4t$

when particle comes to rest,

$\frac{dx}{dt}=0$

$10-4t=0$

$t=\frac{10}{4}$

$t=2.5sec$

The correct option is B.