A body is moving with variable acceleration $(a)$ along a straight line. The average acceleration of body in time interval $t_1$ to $t_2$ is

A car moves from $X$ to $Y$ with a uniform speed $v_1$ and returns to $Y$ with a uniform speed $v_2$ . The average speed for this round trip is

Figure gives the $x-t$ plot of a particle in one-dimensional motion. Three different equal intervals of time are shown. In which interval is the average speed greatest, and in which is it the least ? Give the sign of average velocity for each interval.

Which informations cannot be drawn from average velocity ?

A car travels half the distance with constant velocity of $40\, kmph$ and the remaining half with a constant velocity of $60 \,kmph$. The average velocity of the car in $kmph$ is