Question

If a brick falls from a building 23.0 meters tall, how much time does it take for it to hit the ground?​

Answer 1

Answer:

It will take t = 2.16 [s]

Explanation:

In order to solve this problem, we must find the final speed of the object when it is on the floor. The only way is to use the principle of energy conservation which tells us that potential energy can be transformed into kinetic energy and vice versa.

$E_{p} = E_{k} \\m*g*h = \frac{1}{2} *m*v^{2}$

Now we can find the velocity

v² = 2*g*h

v = √2*9.81*23

v = 21.24 [m/s]

Now using the following equation:

$v_{f} = v_{o} +(g*t)$

where:

Vf = final velocity = 21.24 [m/s]

Vo = initial velocity = 0

g = gravity acceleration = 9.81 [m/s²]

t = time [s]

21.24 = 0 + (9.81*t)

t = 2.16 [s]