What does $\dot x$ represent?

$A$ particle moves along the $x$-axis in such a way that its $x$-coordinate varies with time according to the equation $x = 4 - 2t + t^2$. The velocity of the particle will vary with time as:

We have carefully distinguished between average speed and magnitude of average velocity. No such distinction is necessary when we consider instantaneous speed and magnitude of velocity. The instantaneous speed is always equal to the magnitude of instantaneous velocity. Why?

What is the acceleration of the particle on $OA$,$AB$,and $BC$ respectively?

$A$ bird flies with a velocity $(t-2) \text{ m/s}$ along a straight line, where $t$ is the time in seconds. The distance covered by it in a time of $4 \text{ s}$ is: (in $\text{ m}$)

$A$ body starts from rest and travels a distance $S$ with uniform acceleration,then moves uniformly a distance $2S$ and finally comes to rest after moving further $3S$ under uniform retardation. The ratio of the average velocity to maximum velocity is