An object is moving with variable speed,then

Which one of the following represents the displacement-time graph of two objects $A$ and $B$ moving with zero relative velocity?

The positions of two cars $A$ and $B$ are given by $X_A = at + bt^2$ and $X_B = ft - t^2$. At what time will both cars have the same velocity?

$A$ particle moves along $X$-axis in such a way that its coordinate $x$ varies with time $t$ according to the equation $x = (2 - 5t + 6t^2) \ m$. The initial velocity of the particle is ....... $m/s$.

Find the acceleration of the particle at $x = 5\,m$ using the given $v^2-x$ graph,where $v$ is velocity and $x$ is displacement.

The position $x$ of a particle with respect to time $t$ along the $x$-axis is given by $x = 9t^2 - t^3$,where $x$ is in metres and $t$ is in seconds. What will be the position of this particle when it achieves maximum speed along the $x$-direction?