The motion of a particle is described by the equation $x = a + bt^2$ where $a = 15 \, cm$ and $b = 3 \, cm/s^2$. Its instantaneous velocity at time $t = 3 \, s$ will be ........ $cm/s$.

The graph between the displacement $x$ and time $t$ for a particle moving in a straight line is shown in the figure. Determine the sign of the acceleration of the particle for the intervals $OA$,$AB$,$BC$,and $CD$ respectively.

The $x-t$ graph of a particle moving along a straight line is shown in the figure. The distance-time graph of the particle is correctly shown by:

$A$ bird flies for $4 \, s$ with a velocity of $|t - 2| \, m/s$ in a straight line,where $t$ is time in seconds. It covers a distance of ......... $m$.

The given graph shows the variation of velocity with displacement. Which one of the graphs given below correctly represents the variation of acceleration with displacement?

The displacement-time graph for two particles $A$ and $B$ are straight lines inclined at angles of $30^\circ$ and $60^\circ$ with the time axis. The ratio of velocities $V_A:V_B$ is