The acceleration versus time graph of a body starting from rest is shown in the figure. The velocity versus time graph of the body is given by:

$Assertion$ : Retardation is directly opposite to the velocity.
$Reason$ : Retardation is equal to the time rate of decrease of speed.

The velocity of a particle is given by $v = 2t^2 - 8t + 15 \,ms^{-1}$. Find its instantaneous acceleration at $t = 5 \,s$. (in $\,ms^{-2}$)

What will be the change in the speed of a moving object if both speed and acceleration are positive or both are negative?

The distance-time graph of a particle at time $t$ makes an angle of $45^{\circ}$ with the time axis. After one second,it makes an angle of $60^{\circ}$ with the time axis. What is the average acceleration of the particle?

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?