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4 years ago

Energy transfer by convection is usually restricted to what type of substance?

Physics

2 answers:

dedylja [7]4 years ago

5 0

Answer: The correct answer is fluids.

Explanation:

There are 3 modes of heat transfer that happens:

1. Conduction: In this type of heat transfer, heat is transferred when there is direct contact between the two object.

2. Convection: In this type of heat transfer, heat is transferred when there is a movement of fluid (liquid or gas).

3. Radiation: In this type of heat transfer, heat is transferred when there is direct transfer of energy through space.

Hence, convection is only restricted to fluids which are liquids and gases.

just olya [345]4 years ago

3 0

the anwser is d) fluids

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A ball is thrown vertically up from the edge of a cliff with a speed of 8 m/s, how high is

anygoal [31]

Explanation:

s=d/t

d=s×t

d=8×16.4

d=131.2

distance is 131.2m.

7 0

3 years ago

A commuter train passes a passenger platform at a constant speed of 40.4 m/s. The train horn is sounded at its characteristic fr

mihalych1998 [28]

(a) -83.6 Hz

Due to the Doppler effect, the frequency of the sound of the train horn appears shifted to the observer at rest, according to the formula:

$f' = (\frac{v}{v\pm v_s})f$

where

f' is the apparent frequency

v = 343 m/s is the speed of sound

$v_s$ is the velocity of the source of the sound (positive if the source is moving away from the observer, negative if it is moving towards the observer)

f is the original frequency of the sound

Here we have

f = 350 Hz

When the train is approaching, we have

$v_s = -40.4 m/s$

So the frequency heard by the observer on the platform is

$f' = (\frac{343 m/s}{343 m/s - 40.4 m/s})(350 Hz)=396.7 Hz$

When the train has passed the platform, we have

$v_s = +40.4 m/s$

So the frequency heard by the observer on the platform is

$f' = (\frac{343 m/s}{343 m/s + 40.4 m/s})(350 Hz)=313.1 Hz$

Therefore the overall shift in frequency is

$\Delta f = 313.1 Hz - 396.7 Hz = -83.6 Hz$

And the negative sign means the frequency has decreased.

(b) 0.865 m

The wavelength and the frequency of a wave are related by the equation

$v=\lambda f$

where

v is the speed of the wave

$\lambda$ is the wavelength

f is the frequency

When the train is approaching the platform, we have

v = 343 m/s (speed of sound)

f = f' = 396.7 Hz (apparent frequency)

Therefore the wavelength detected by a person on the platform is

$\lambda' = \frac{v}{f'}=\frac{343 m/s}{396.7 Hz}=0.865m$

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3 years ago

When two substances are mixed together, a color change is observed. Does this mean that a chemical reaction has definitely occur

Elanso [62]

Nope, color change can also occur during a physical change.

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3 years ago

Magma that cools and crystallizes on Earth's surface forms

Nostrana [21]

The correct answer is:

D. Extrusive rocks.

The explanation:

when extrusive igneous rocks form when magma reaches the Earth's surface a volcano and cools quickly. Most extrusive (volcanic) rocks have small crystals. Examples include basalt, rhyolite, andesite, and obsidian.

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4 years ago

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miss Akunina [59]

Answer:

An attraction between two objects that have mass :)

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3 years ago