3 years ago

Identify the true statement. Choose one:

Physics

1 answer:

beks73 [17]3 years ago

4 0

Answer:

A. Underground coal mining is dangerous because of possible tunnel collapse and possible methane gas explosions.

Explanation:

Dangers of underground coal mining include asphyxiation, methane gas poisoning, tunnel collapse and explosions of methane gas, a highly flammable gas. Methane explosions occur since this gas is a byproduct of coal. This explosion can cause tunnel collapse.

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An FM radio station broadcasts electromagnetic radiation at a frequency of 93.5 MHz. The wavelength of this radiation is _______

Alborosie

Answer:

3.21

Explanation:

The relation between frequency and wavelength is shown below as:

$c=frequency\times Wavelength
$

c is the speed of light having value $3\times 10^8\ m/s$

Given, Frequency = 93.5 MHz = $93.5\times 10^{6}\ Hz$

Thus, Wavelength is:

$Wavelength=\frac{c}{Frequency}$

$Wavelength=\frac{3\times 10^8}{93.5\times 10^{6}}\ m$

$Wavelength=3.21 \ m$

<u>Answer - A.</u>

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3 years ago

The density of table sugar is 1.59 g/cm3. What is the volume of 7.85 g of sugar?

Likurg_2 [28]

$\frac{7.85g }{1.59 \frac{g}{ cm^{3} } }$ = 4.937 $cm^{3}$

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3 years ago

an ice skater applies a horizontal force to a 20.-kilogram block on frictionless, level ice, causing the block to accelerate uni

stiv31 [10]

The only vertical forces are weight and normal force, and they balance since the surface is horizontal. The horizontal forces are the applied force (uppercase F) in the direction the block slides and the frictional force (lowercase f) in the opposite direction.

Apply Newton's 2nd Law in the horizontal direction:
ΣF = ma
F - f = ma
where f = µmg

F - µmg = ma
F = m(a +µg)
F = (20 kg)(1.4 m/s² + 0.28(9.8 m/s²)

F = 83 N

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3 years ago

How long will a trip take in hours of you travel 450kmat an average speed of 80 km/hr

777dan777 [17]

5.625 hours and it is 450 divided by 80
Have A Good Day

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3 years ago

4. Explain how states of matter change in regards to<br> a. Temperature-<br> b. Pressure-

Alina [70]

Temperature can change the state from solid to liquid causing it to melting, liquid to gas causing vaporization or a solid to a gas causing sublimation. Pressure alone cannot change the state of matter.

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3 years ago