$A$ particle moving in a straight line covers half the distance with a speed of $3 \, m/s$. The other half of the distance is covered in two equal time intervals with speeds of $4.5 \, m/s$ and $7.5 \, m/s$ respectively. The average speed of the particle during this motion is...... $\, m/s$

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

The position of an object moving along the $X$-axis is given by $x = \alpha + \beta t^2$,where $\alpha$ and $\beta$ are constants with appropriate dimensions and $t$ is time in seconds. The average velocity between $t = 2 \ s$ and $t = 4 \ s$ is $12 \ m/s$. If $\alpha = 8 \ m$,then the value of $\beta$ is: (in $m/s^2$)

The position of an object moving along the $x$-axis is given by $x = a + b t^2$,where $a = 8.5 \; m$,$b = 2.5 \; m s^{-2}$,and $t$ is measured in seconds. What is the average velocity between $t = 2.0 \; s$ and $t = 4.0 \; s$ (in $; m s^{-1}$)?

Is it possible for a moving object to have a constant velocity and a changing speed?

Velocity of an object in rectilinear motion is given as a function of time by $v = t - t^3$,where $v$ is in $m/s$ and $t$ is in seconds. Its average velocity over the time interval from $t = 0 \ s$ to $t = 2 \ s$ is ........ $m/s$.