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3 years ago

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 2.01 seconds.

How fast does it hit the ground?

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

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When passing another vehicle you are allowed to exceed the speed limit by?

lesantik [10]

If the other driver is going speed limit you can't pass him but if he's going slower than the limit you have to go in the left lane i'm not sure by how much i'll guess 5mph

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3 years ago

A crate rests on a flatbed truck which is initially traveling at 17.9 m/s on a level road. The driver applies the brakes and the

Mamont248 [21]

Answer:

The minimum coefficient of friction required is 0.35.

Explanation:

The minimum coefficient of friction required to keep the crate from sliding can be found as follows:

$-F_{f} + F = 0$

$-F_{f} + ma = 0$

$\mu mg = ma$

$\mu = \frac{a}{g}$

Where:

μ: is the coefficient of friction

m: is the mass of the crate

g: is the gravity

a: is the acceleration of the truck

The acceleration of the truck can be found by using the following equation:

$v_{f}^{2} = v_{0}^{2} + 2ad$

$a = \frac{v_{f}^{2} - v_{0}^{2}}{2d}$

Where:

d: is the distance traveled = 46.1 m

$v_{f}$ : is the final speed of the truck = 0 (it stops)

$v_{0}$ : is the initial speed of the truck = 17.9 m/s

$a = \frac{-(17.9 m/s)^{2}}{2*46.1 m} = -3.48 m/s^{2}$

If we take the reference system on the crate, the force will be positive since the crate will feel the movement in the positive direction.

$\mu = \frac{a}{g}$

$\mu = \frac{3.48 m/s^{2}}{9.81 m/s^{2}}$

$\mu = 0.35$

Therefore, the minimum coefficient of friction required is 0.35.

I hope it helps you!

4 0

3 years ago

The law of universal gravitation states that a gravitational force exists between all objects in the universe. This force is dir

Ber [7]

Answer: D. it has been demonstrated to be without exception under certain stated conditions.

Explanation:

A Law is an affirmation (something established) based on repeated long-term observation of a phenomenon that has been studied and verified.

That is: A law is present in all known theories and therefore is considered universal. In addition, a law can not be refuted, nor changed, because its precepts have been proven through various studies.

Unlike theory, which is the set of rules and principles that describe and explain a particular phenomenon and is subject to changes as new evidence emerges that gives meaning to it.

Then, based on what is explained above, the law of universal gravitation is a statement that exists because it was rigorously tested and verified, therefore it can not be refuted.

3 0

3 years ago

Holding onto a tow rope moving parallel to a frictionless ski slope, a 70.1 kg skier is pulled up the slope, which is at an angl

lara [203]

Answer:

given,

mass of the skier = 70.1 Kg

angle with horizontal, θ = 8.6°

magnitude of the force,F = ?

a) Applying newton's second law

$m g sin\theta - F_{rope} = ma$