What does a vehicle's speedometer measure: instantaneous velocity or instantaneous speed?

The area $A$ of a blot of ink is growing such that after $t$ seconds its area is given by $A = (3t^2 + 7) \, cm^2$. Calculate the rate of increase of area at $t = 2 \, s$. .......... $cm^2/s$

The positions of two cars $A$ and $B$ are given by $X_A = at + bt^2$ and $X_B = ft - t^2$. At what time will both cars have the same velocity?

Can the position-time graph of a moving object be parallel to the position axis? Why?

$A$ particle moves according to the equation $x = a + bt^2$,where $a = 15 \, cm$ and $b = 3 \, cm/s^2$. What is the velocity of the particle at $t = 3 \, s$ in $cm/s$?

$A$ rigid ball rolls without slipping on a surface shown below: Which one of the following is the most likely representation of the distance travelled by the ball versus time graph?