A car moves a distance of $200 \;m$. It covers the first half of the distance at speed $40 \;km / h$ and the second half of distance at speed $v$. The average speed is $48\; km / h$. The value of $v$ is

If the body covers one-third distance at speed $v_1$, next one third at speed $v_2$ and last one third at speed $v_3$, then average speed will be

Give difference between average speed and average velocity.

A car goes from $A$ to $B$ (without changing direction), during first part of journey its average speed is $V_1$ and for second part of journey average speed is $V_2$ . The ratio path length of second part to the path length of first part is $\sqrt {\frac{{{V_2}}}{{{V_1}}}} $ . In that case the average speed of total path is ....... of average speeds of both parts. Choose correct option of fill. 

A particle moving in a straight line covers half the distance with speed $6 \mathrm{~m} / \mathrm{s}$. The other half is covered in two equal time intervals with speeds 9 $\mathrm{m} / \mathrm{s}$ and $15 \mathrm{~m} / \mathrm{s}$ respectively. The average speed of the particle during the motion is :

Which among average speed and average velocity can be positive, negative or zero ?