$A$ 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? ......... $m$

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 ......... $m/s$.

$A$ man walks on a straight road from his home to a market $2.5 \; km$ away with a speed of $5 \; km \; h^{-1}$. Finding the market closed,he instantly turns and walks back home with a speed of $7.5 \; km \; h^{-1}$. What is the average speed of the man over the interval of time $0$ to $30 \; min$?

$A$ man walks on a straight road from his home to a market $2.5 \; km$ away with a speed of $5 \; km \; h^{-1}$. Finding the market closed,he instantly turns and walks back home with a speed of $7.5 \; km \; h^{-1}$. What is the average speed (in $km/h$) of the man over the interval of time $0$ to $50 \; min$?

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

$A$ person goes from point $P$ to point $Q$ covering $1/3$ of the distance with speed $10 \, km/h$,the next $1/3$ of the distance at $20 \, km/h$,and the last $1/3$ of the distance at $60 \, km/h$. The average speed of the person is ............ $km/h$.