The displacement ‘x’ (in meter) of a particle of mass ‘m’ (in kg) moving in one dimension under the action of a force, is related to time ‘t’ (in sec) by $t=\sqrt{x}+3$. The displacement of the particle when its velocity is zero, will be

Displacement (x) of a particle is related to time (t) as

$t=\sqrt{x}+3$

so,  $\sqrt{x}=t-3$

$x=t^2-6t+9$.........(1)

We need to find out displacement when velocity is zero.
Differentiating equation (1), we get

$\text{Velocity }V=\frac{dx}{dt}=2t-6$

V will be zero when 2t - 6 = 0

$\mathrm{t}=\frac{6}{2}=3\mathrm{s}$.

Displacement when t = 3, we obtain by putting t = 3 in equation (1).

$x=(3{)}^2-6\times 3+9=0$

Hence, when velocity is zero, its displacement will also be zero.