The position $(x)$-time $(t)$ graph for a particle moving along a straight line is shown in the figure. The average speed of the particle in the time interval $t=0$ to $t=8 \, s$ is .......... $m/s$.

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

In $1.0 \, s$,a particle moves from point $A$ to point $B$ along a semicircle of radius $1.0 \, m$ (see figure). The magnitude of the average velocity is ......... $m/s$.

Consider a particle moving along a straight line, whose position as a function of time is given by $s(t) = \alpha t^2 - \beta t + \gamma$, where $\alpha = 1 \text{ ms}^{-2}$, $\beta = 6 \text{ ms}^{-1}$ and $\gamma = 5 \text{ m}$. The average speed of the particle, in $\text{ms}^{-1}$, from $t = 0$ to $t = 6 \text{ s}$ is :

$A$ car starts from rest and moves such that it possesses average speeds of $5 \, ms^{-1}$,$10 \, ms^{-1}$,and $15 \, ms^{-1}$ in the first,second,and third seconds,respectively. What is the total distance covered by the car in these three seconds? ......... $m$

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