Question

A car falls off a bridge and drops to the ground in $0.5s$. Let $g=10m/s^2$. How high is the bridge from the ground?

• A. $1.25m$
• B. $2.5m$
• C. $5m$
• D. $10m$

Answer 1

Answer: (A)

$1.25m$

Answer is A.
In this case, the distance traveled by the car off to the ground is equal to the total height of the bridge.
So, 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,
$s=0\times 0.5+\frac{1}{2}\times 10\times {0.5}^2=1.25m.$

Hence, the height of the bridge is 1.25 m.