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Lera25 [3.4K]
3 years ago
11

A body is dropped from the roof of a 20 m high building by how much:

Physics
1 answer:
USPshnik [31]3 years ago
7 0

Answer:

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:

  • Height (h) = 20 m
  • Gravity (g) = 9.8 m/s²
  • Time (t) = ?
  • Final Velocity (Vf) = ?

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

Time

Use formula:

  • \boxed{t=\sqrt{\frac{2*h}{g}}}

Replace:

  • \boxed{t=\sqrt{\frac{2*20m}{9.8\frac{m}{s^{2}}}}}

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

  • \boxed{t=\sqrt{\frac{40m}{9.8\frac{m}{s^{2}}}}}

It divides:

  • \boxed{t=\sqrt{4.08s}}

The square root is performed:

  • \boxed{t=2.01s}

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

Final Velocity

use formula:

  • Vf = g * t

Replace:

  • Vf = 9.8 m/s² * 2.01 s

Multiply:

  • Vf = 19.7 m/s

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

How long does it take to reach the ground?

Takes time to reach the ground in <u>2.01 seconds.</u>

How fast does it hit the ground?

Hits the ground with a speed of <u>19.7 meters per seconds.</u>

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Answer:

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        \frac{1}{2} * m* v^{2} = W_{ffr} - \Delta U = W_{ffr} - (U_{f} -U_{o})  (6)

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