A car travels from $A$ to $ B $ at a speed of $20\,\,km/hr$ and returns at a speed of $30\,\,km/hr$. The average speed of the car for the whole journey is............$km/hr$

A motor cyclist travels a certain distance with a uniform speed of $30\, m/s$ and immediately turns back and returns to starting point with a uniform speed $20\, m/s$. Then the average speed of the motor cycle is ..........$m/s$ :-

A body has speed $V, 2V$ and $3V$ in first $1/3$ of distance $S$, seconds $1/3$ of $S$ and third $1/3$ of $S$ respectively. Its average speed will be

Give difference between average speed and average velocity.

A boy walks to his school at a distance of $6\, km$ with constant speed of $2.5\, km/hour $ and walks back with a constant speed of $4 \,km/hr.$ His average speed for round trip expressed in $km/hour$, is

The speed-time graph of a particle moving along a fixed direction is shown in Figure 

$(a)\; t = 0\; s$ to $10 \;s$, $(b)\;t=2 \;s$ to $6\; s$

What is the average speed of the particle over the intervals in $(a)$ and $(b)$?