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3 years ago

Find the noise level of a sound having an intensity of 1.5x10^-14W/m^2 given I0=10^12 W/m2

Physics

1 answer:

Llana [10]3 years ago

5 0

Answer:

Noise level will be -18.2 watt

So option (b) will be correct answer

Explanation:

We have given sound intensity $I=1.5\times 10^{-14}w/m^2$

And threshold intensity $I_0=\times 10^{-12}w/m^2$ ( in question it is given as $10^{12}w/m^2$ but its standard value is $10^{-12}w/m^2$ )

Now noise level $=10log\frac{I}{I_0}=10log\frac{1.5\times 10^{-14}}{10^{-12}}=10log0.015-18.23$

So the noise level will be -18.2

So option (b) will be correct answer

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A small sphere is hung by a string from the ceiling of a van. When the van is stationary, the sphere hangs vertically. However,

Paraphin [41]

Answer: 42.49 $m/s^{2}$

Explanation:

To solve this, we need to keep in mind the following:

While the sphere hangs it is under the effect of gravity. It is creating a Angle of 90° taking the roof as a reference.

Gravity can be noted as a Acceleration Vector. The magnitud for Earth's Gravity is a constant: 9.81 $m/s^{2}$

The acceleration of the Van will affect the sphere also, but this accelaration will be on the X-axis and perpendicular to the gravity. Because this two vectors are taking action under the sphere they will create a angle. This angle can be measured as a relation of the two magnitudes.

Tangent (∅) = Opossite Side / Adyacent Side

By trigonometry, we know the previous formula. This formula allows us to find the Tangent of a angle as a relation between the two perpendiculars magnitudes. In this case the Opossite Side will be the Gravity Accelaration, while the Adyancent Side is the Van's Acceleration.

(1) Tangent (∅) = Gravity's Acceleration (G) / Van's Acceleration (Va)

Searching for the Va in (1)

Va = G/Tan(∅)

Where ∅ in this case is equal to 13.0°

Va = 9.81 $m/s^{2}$ / Tan(13.0°)

Va = 42.49 $m/s^{2}$

The vans acceleration need to be 42.49 $m/s^{2}$ to create an angle of 13° with the Van's Roof

3 0

3 years ago

Insulators will:

nalin [4]

Answer:

Inhibit the flow of electrons

Explanation:

An electric current usually consists of electrons moving through a wire.

An insulator prevents the flow of an electric current, so it inhibits the flow of electrons.

7 0

3 years ago

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What is the significance of a standard system of measurement?

dimulka [17.4K]

Because scientists all over the world are working together, looking for answers to the same questions, just as much as if they all worked in the same physical laboratory in the same building. They need a way to share data and experimental results in a form that everyone can understand. ( D )

Let's say I perform an experiment and get very exciting results. I'm a good scientist, so the next thing I want to do is to publish a complete description of how I did my experiment, and include all of my results. That way, scientists around the world can read about what I did, they can find any mistakes that I made, and they can even repeat my experiment for themselves and see if they get the same results.

Now let's say that my results looked like this:

Result #1).

The reaction stabilized when it reached the rate of 1.26 briligs per tove.

Result #2).

After running at that constant rate for 35 toves, a pile of product was produced whose mass was exactly 61.284 wibbles.

Result #3).

When the pile of product was allowed to settle for another 20 toves, it had spread out, and covered an area of 14.907 square filks.

Do YOU understand my results ?

All those other scientists would have a tough time trying to decide whether my results made sense. And if they repeated my experiment, they would have no way to tell whether their results matched mine or not.

Without a standard system of measurement, and units that mean the same thing to everybody, us scientists literally could not communicate.

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3 years ago

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Two cars, initially at rest and 5 km apart at t=0 , simultaneously move toward each other. Car A travels at a constant speed of

Anastasy [175]

Answer:

Explanation:

<u>Constant Speed Motion</u>

An object is said to travel at constant speed if the ratio of the distance traveled by the time taken is constant.

Expressed in a simple equation, we have:

$\displaystyle v=\frac{d}{t}$

Where

v = Speed of the object

d = Distance traveled

t = Time taken to travel d.

From the equation above, we can solve for d:

d = v . t

And we can also solve it for t:

$\displaystyle t=\frac{d}{v}$

Two cars are initially separated by 5 km are approaching each other at relative speeds of 55 km/h and 12 km/h respectively. The total speed at which they are approaching is 55+12 = 67 km/h.

The time it will take for them to meet is:

$\displaystyle t=\frac{5}{67}$

t = 0.0746 hours

Converting to seconds: 0.0746*3600 = 268.56

The closest answer is d. 268 s

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3 years ago

What force keeps our atmosphere from floating out into space?

Tems11 [23]

The answer is C, gravity

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