A car falls off a bridge and drops to the ground in $0.5s$. Let $g=10m/s^2$ the what is its average speed during $0.5s$ ?

The correct option is B $2.5m/s$
Answer is B.
The total distance traveled by the falling car to the ground is calculated as follows.

$s=ut+\frac{1}{2}a{t}^2$ where,
$s$ - distance covered
$u$ - initial velocity which is 0 in this case
$a$- acceleration due to gravity which is $10m/s^2$
$t$- 0.5 seconds

Substituting these values in the given equation we get,
$s=0\times 0.5+\frac{1}{2}\times 10\times {0.5}^2=1.25m$

The average speed is calculated using the formula, $Averagespeed=\frac{distance}{time}m/s$

Therefore, $Averagespeed=\frac{1.25m}{0.5s}=2.5m/s.$

Hence, the average speed in which the car falls to the ground is 2.5 m/s.