$A$ train has a speed of $60\, km/h$ for the first one hour and $40\, km/h$ for the next half hour. Its average speed in $km/h$ is

The position of an object moving along the $X$-axis is given by $x = \alpha + \beta t^2$, where $\alpha$ and $\beta$ are constants with appropriate dimensions and $t$ is time in seconds. The average velocity between $t = 2 \ s$ and $t = 4 \ s$ is $12 \ m/s$. If $\alpha = 8 \ m$, then the value of $\beta$ is: (in $m/s^2$)

$A$ bus travels the first one-third distance at a speed of $10\; km/h$,the next one-third at $20\; km/h$,and the last one-third at $60\; km/h$. The average speed of the bus is ........ $km/h$.

$A$ person travels along a straight road for half the distance with velocity $v_1$ and the remaining half distance with velocity $v_2$. The average velocity is given by:

$A$ person travels along a straight road for the first half time with a velocity $v_1$ and the next half time with a velocity $v_2$. The mean velocity $V$ of the man is

Define velocity. Define average velocity.