A body is dropped from the roof of a 20 m high building by how much: Does it take to reach the ground? How fast does it hit the ground?

t = 2.01 s

Vf = 19.7 m/s

Explanation:

It's know through the International System that the earth's gravity is 9.8 m/s², then we have;

Data:

==================================================================

Time

Use formula:

Replace:

Everything inside the root is solved first. So, we solve the multiplication of the numerator:

It divides:

The square root is performed:

==================================================================

Final Velocity

use formula:

Replace:

Multiply:

==================================================================

How long does it take to reach the ground?

Takes time to reach the ground in 2.01 seconds.

How fast does it hit the ground?

Hits the ground with a speed of 19.7 meters per seconds.

the pull of gravity on the rocket decreases