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3 years ago

Describe the Dark Ages of our universe.

1 answer:

4 0

When the universe<span> was young, there was a time when it was empty of the stars and galaxies and planets we see today. This basically means that there was a loss of energy in the universe.</span>

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Que formas de energía utilizas habitualmente?

Luda [366]

Esta energía<span> puede ser convertida en otras, como calor para calentar agua o edificios, invernaderos etc. o electricidad. Podemos convertir la </span>energía<span> solar en eléctrica de dos </span>formas<span>: Fotovoltáica (PV): La radiación solar se convierte directamente en electricidad

hope this help mark brainliest plz</span>

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2 years ago

1. A listener stands 20.0 m from a speaker that pumps out music with a power output of 100.0 W.

marta [7]

(1.a) The surface area being vibrated by the time the sound reaches the listener is 5,026.55 m².

(1.b) The intensity of the sound wave as it reaches the person listening is 0.02 W/m².

(1.c) The relative intensity of the sound as heard by the listener is 103 dB.

(2.a) The speed of sound if the air temperature is 15⁰C is 340.3 m/s.

(2.b) The frequency of the sound heard by the suspect is 614.3 Hz.

<h3>Surface area being vibrated</h3>

The surface area being vibrated by the time the sound reaches the listener is calculated as follows;

A = 4πr²

A = 4π x (20)²

A = 5,026.55 m²

<h3>Intensity of the sound</h3>

The intensity of the sound is calculated as follows;

I = P/A

I = (100) / (5,026.55)

I = 0.02 W/m²

<h3>Relative intensity of the sound</h3>

$B = 10log(\frac{I}{I_0} )\\\\B = 10 \times log(\frac{0.02}{10^{-12}} )\\\\B = 103 \ dB$

<h3>Speed of sound at the given temperature</h3>

$v= 331.3\sqrt{1 + \frac{T}{273} } \\\\v = 331.3\sqrt{1 + \frac{15}{273} } \\\\v = 340.3 \ m/s$

<h3>Frequency of the sound</h3>

The frequency of the sound heard is determined by applying Doppler effect.

$f_o = f_s(\frac{v \pm v_0}{v \pm v_s} )$

where;

-v₀ is velocity of the observer moving away from the source
-vs is the velocity of the source moving towards the observer
fs is the source frequency
fo is the observed frequency
v is speed of sound

$f_0 = f_s(\frac{v-v_0}{v- v_s} )$

$f_0 = 512(\frac{340.3 - 10}{340.3 - 65} )\\\\f_0 = 614.3 \ Hz$

Learn more about intensity of sound here: brainly.com/question/17062836

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1 year ago

Answer question 83 and 84

Ne4ueva [31]

83. Gravity is activity as a force on the cart.

84. The box has gathered kinetic energy and momentum and will continue going forward.

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2 years ago

Why does the cord of an electric heater not glow while the heating element does

Strike441 [17]

Answer: Why does the cord of an electric heater not glow while the heating element does? The heating element of the heater is made up of alloy which has very high resistance so when current flows through the heating element, it becomes too hot and glows red. But the resistance of cord which is usually of copper or aluminum is very low so it does not glow.

Explanation:

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2 years ago

When the rubber sheet is pulled down, the volume of the bell jar is ____________ and the pressure in the bell jar is ___________

Makovka662 [10]

Answer:

increases, decreases, respiration

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1 year ago