What does the slope of the velocity$-$time graph represent?

$A$ bus decreases its speed from $80 \, km \, h^{-1}$ to $50 \, km \, h^{-1}$ in $4 \, s$. Find the acceleration of the bus.

If the displacement of a body is proportional to the square of the time elapsed,what type of motion does the body possess?

$A$ train starting from a railway station and moving with uniform acceleration attains a speed $40 \, km \, h^{-1}$ in $10$ minutes. Find its acceleration (in $m / s^{2}$).

$A$ moving body is covering a distance directly proportional to the square of time. The acceleration of the body is

If the average velocity of a body is equal to the mean of its initial velocity and final velocity,then the acceleration of the body is