A car starts from rest and moves with uniform acceleration a on a straight road from time $t = 0$ to $t = T$. After that, $a$ constant deceleration brings it to rest. In this process the average speed of the car is
$\frac{{aT}}{4}$
$\frac{{3aT}}{2}$
$\frac{{aT}}{2}$
$aT$
A $100\, m$ long train is moving with a uniform velocity of $45\, km/hr$. The time taken by the train to cross a bridge of length $1 \,km$ is.........$s$
A car is moving along a straight line, say $OP$ in given figure. It moves from $O$ to $P$ in $18\; s$ and returns from $P$ to $\mathrm{Q}$ in $6.0\; s$. What are the average velocity and average speed of the car in going from $O$ to $P$ and back to $Q?$
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 $150 \,m$ long train is moving with a uniform velocity of $45 \,km/h$. The time taken by the train to cross a bridge of length $850 $ meters is..........$sec$
A car travels a distance $S$ on a straight road in two hours and then returns to the starting point in the next three hours. Its average velocity is