Question

If an object is dropped from rest off a 10.5m high building, how long does it take to hit the ground?

Answer 1

We can calculate the time it takes for the object to hit the ground by using the following equation:

$S=\frac{1}{2} gt^2$

where S=10.5 m is the initial height of the object, $g=9.81 m/s^2$ is the free-fall acceleration and t is the time. Re-arranging the equation, we can solve for the time:

$t=\sqrt{\frac{2S}{g}}=\sqrt{\frac{2(10.5 m)}{9.81 m/s^2}}=1.46 s$