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2 years ago

Instructions:Select all the correct answers.

Physics

2 answers:

malfutka [58]2 years ago

4 0

The correct answer is 1 and 4.

Burning of fossil fuels releases harmful gases to the atmosphere which leads to climate change. Burning of hydrogen gas releases water which has no negative effect on climate.

Burning of both fossil fuels and hydrogen takes place inside expensive fuel cells.

Fossil fuels are widely available and easy to locate whereas hydrogen is available in the combined form with other elements. Hydrogen are not found in pure form on earth.

Fossil fuels are non-renewable source of energy which means they cannot be replaced in short time.

pogonyaev2 years ago

4 0

1 & 4 would be what you looking for

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. A dog walks 14 m to the east and then 20 m back to the west. What is the distance? What is the displacement?

Crank

Answer:

Hi...

14-20=-6...displacement

14+20=34...distance

3 0

2 years ago

The radius of earth is 6,370,000 m. Express this measurement in km in scientific notation with the correct number of significant

AlexFokin [52]

Answer:

6.37 x 10³ Km

Explanation:

given,

Radius of earth = 6,370,000 m

we know,

1 km = 1000 m

1 m = 0.001 Km

6,370,000 m = 6,370,000 x 0.001

= 6,370 Km

The number 6,370 has 3 significant figure.

To transform this to an exponential number, it is necessary to move the decimal to the left so there is only one digit in front of the decimal point.

Representing the given number in scientific notation

= 6.37 x 10³ Km

7 0

3 years ago

7.22 Ignoring reflection at the air–water boundary, if the amplitude of a 1 GHz incident wave in air is 20 V/m at the water surf

Serga [27]

Answer:

z = 0.8 (approx)

Explanation:

given,

Amplitude of 1 GHz incident wave in air = 20 V/m

Water has,

μr = 1

at 1 GHz, r = 80 and σ = 1 S/m.

depth of water when amplitude is down to 1 μV/m

Intrinsic impedance of air = 120 π Ω

Intrinsic impedance of water = $\dfrac{120\pi}{\epsilon_r}$

Using equation to solve the problem

$E(z) = E_0 e^{-\alpha\ z}$

E(z) is the amplitude under water at z depth

E_o is the amplitude of wave on the surface of water

z is the depth under water

$\alpha = \dfrac{\sigma}{2}\sqrt{\dfrac{(120\pi)^2}{\Epsilon_r}}$

$\alpha = \dfrac{1}{2}\sqrt{\dfrac{(120\pi)^2}{80}}$

$\alpha =21.07\ Np/m$

now ,

$1 \times 10^{-6} = 20 e^{-21.07\times z}$

$e^{21.07\times z}= 20\times 10^{6}$

taking ln both side

21.07 x z = 16.81

z = 0.797

z = 0.8 (approx)

5 0

3 years ago

Which of the following elements is in the same period as phosphorus?

Arte-miy333 [17]

The answer is B. magnesium I am pretty sure

5 0

3 years ago

Plzzz help will give brainlist

zhenek [66]

Answer:

Explanation:

this would make sense but it seems to be more like they both sound different

5 0

2 years ago