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

Between the two stations a train accelerates uniformly at first, then moves with constant velocity and finally retards uniformly. If the ratio of the time taken be $1 : 8 : 1$ and the maximum speed attained be $60\,km/h,$ then what is the average speed over the whole journey.......$km/h$

A particle moves along the sides $AB, BC, CD$ of a square of side $25 \,m$ with a velocity of $15$$m{s^{ - 1}}.$ Its average velocity is........$m{s^{ - 1}}$

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 $100\, m$ long train is moving with a uniform velocity of $45\, km/hr$. The time taken by the train to cross a bridge of length $1 \,km$ is.........$s$