If the speed of a moving object decreases,what are the directions of its velocity and acceleration?

$A$ particle moves along a straight line such that its displacement at any time $t$ is given by $s = (t^3 - 3t^2 + 2) \, m$. The displacement when the acceleration becomes zero is ........ $m$.

The acceleration of a train between two stations is shown in the figure. The maximum speed of the train is $............\,m/s$.

Will the acceleration increase or decrease with an increase in velocity?

Match the following columns.

Column $I$	Column $II$
$(A)$ $\frac{dv}{dt}$	$(p)$ Acceleration
$(B)$ $\frac{d|v|}{dt}$	$(q)$ Magnitude of acceleration
$(C)$ $\frac{dr}{dt}$	$(r)$ Velocity
$(D)$ $\left|\frac{dr}{dt}\right|$	$(s)$ Magnitude of velocity

The graph of position $x$ versus time $t$ represents the motion of a particle. The curve is a parabola opening upwards. If the equation of motion is given by $x = a + bt - ct^2$ where $b$ and $c$ are positive constants,which of the following expressions best describes the acceleration $a_{acc}$ of the particle?