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Zielflug [23.3K]
3 years ago
7

Physical Science Pre-Test 2020-2021 Question: 1-10 The distance between Earth and the Moon was determined by measuring the time

it took for light waves from Earth to travel to the Moon and back. Why was it not possible to use sound waves for this experiment Sound waves must move through a substance Sound waves would change frequency on the return to Earth Sound waves move too slowly for the technique to be accurate Sound waves move more slowly in Earth's atmosphere than in space​
Physics
1 answer:
LiRa [457]3 years ago
5 0

Answer:

Option A - Sound waves must move through a substance

Explanation:

Unlike light waves, sound waves must travel through a medium/substance for such a medium to vibrate and then produce sound.

As a matter of fact sound can't travel through empty space.

Thus, looking at the options given, the correct one is:

Sound waves must move through a substance which is Option A

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The velocity component with which a projectile covers certain horizontal distance is maximum at the moment of? a) Hitting the gr
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A) hitting the ground
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Question C) needs to be answered, please help (physics)
Zarrin [17]

(a) Differentiate the position vector to get the velocity vector:

<em>r</em><em>(t)</em> = (3.00 m/s) <em>t</em> <em>i</em> - (4.00 m/s²) <em>t</em>² <em>j</em> + (2.00 m) <em>k</em>

<em>v</em><em>(t)</em> = d<em>r</em>/d<em>t</em> = (3.00 m/s) <em>i</em> - (8.00 m/s²) <em>t</em> <em>j</em>

<em></em>

(b) The velocity at <em>t</em> = 2.00 s is

<em>v</em> (2.00 s) = (3.00 m/s) <em>i</em> - (16.0 m/s) <em>j</em>

<em></em>

(c) Compute the electron's position at <em>t</em> = 2.00 s:

<em>r</em> (2.00 s) = (6.00 m) <em>i</em> - (16.0 m) <em>j</em> + (2.00 m) <em>k</em>

The electron's distance from the origin at <em>t</em> = 2.00 is the magnitude of this vector:

||<em>r</em> (2.00 s)|| = √((6.00 m)² + (-16.0 m)² + (2.00 m)²) = 2 √74 m ≈ 17.2 m

(d) In the <em>x</em>-<em>y</em> plane, the velocity vector at <em>t</em> = 2.00 s makes an angle <em>θ</em> with the positive <em>x</em>-axis such that

tan(<em>θ</em>) = (-16.0 m/s) / (3.00 m/s)   ==>   <em>θ</em> ≈ -79.4º

or an angle of about 360º + <em>θ</em> ≈ 281º in the counter-clockwise direction.

3 0
3 years ago
10. Convert the following:<br> a. 37.4 mL into ML<br> b. 689 km/hr into m/s<br> c. 34.5 m² into mm²
Snezhnost [94]

A. When we convert 37.4 mL to ML, the result obtained is 3.74×10¯⁸ ML

B. When we convert 689 km/hr to m/s, the result obtained is 191.39 m/s

C. When we convert 34.5 m² to mm², the result obtained is 3.45×10⁷ mm²

<h3>A. How to convert millimeters (mL) to megaliter (ML)</h3>
  • Volume (mL) = 37.4 mL
  • Volume (ML) =?

1 mL = 1×10¯⁹ ML

Therefore,

37.4 mL = 37.4 × 1×10¯⁹

37.4 mL = 3.74×10¯⁸ ML

Thus, 37.4 mLis equivalent to 3.74×10¯⁸ ML

<h3>B. How to convert 689 km/hr to m/s</h3>

Conversion scale

3.6 Km/hr = 1 m/s

Therefore,

689 km/hr = 689 / 3.6

689 km/hr = 191.39 m/s

Thus, 689 km/hr is equivalent to 191.39 m/s

<h3>C. How to convert 34.5 m² to mm²</h3>

Conversion scale

1 m² = 1×10⁶ mm²

Therefore,

34.5 m² = 34.5 × 1×10⁶

34.5 m² = 3.45×10⁷ mm²

Thus, 34.5 m² is equivalent to 3.45×10⁷ mm²

Learn more about conversion:

brainly.com/question/2139943

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1 year ago
Please help! 100 points!
gregori [183]

Answer:

1.Nitrification happens when soil organisms change over ammonium into nitrate. Much of the cover between the carbon cycle and the nitrogen cycle happens within the soil, in forms conducted by soil organisms. Organisms break down supplements, construct modern compounds for their possess development, and inevitably pass on.

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3. Many human activities have a significant impact on the nitrogen cycle. Burning fossil fuels, application of nitrogen-based fertilizers, and other activities can dramatically increase the amount of biologically available nitrogen in an ecosystem. As nitrogen makes up 78% of the atmosphere, there is no shortage of it – it just isn't in a form plants and animals can use.

4. Carbon makes its way through living things as carbon-based compounds, like vitality particles, fats and proteins, in the long run cycling its way back into the environment. Nitrogen is basically found within the air as well and enters the environments as supplements for plants. Water, nitrogen and carbon cycles. Carbon moves from the air and back by means of creatures and plants. Nitrogen moves from the environment and back by means of living beings. Water moves on, over, or underneath the surface of the Soil.

5. Carbon cycle, Nitrogen cycle, Nutrient cycle, Oxygen cycle, Phosphorus cycle, Sulfur cycle, Rock cycle, Water cycle.

6. Wind, water, and ice disintegrate and shape the arrive. Volcanic movement and seismic tremors change the scene in a sensational and frequently savage way. And on a much longer timescale, the development of earth's plates gradually reconfigures seas and landmasses. Each one of these forms plays a part within the Cold and Antarctica.

People affect the physical environment in numerous ways: overpopulation, contamination, burning fossil powers, and deforestation. Changes like these have activated climate alter, soil disintegration, destitute discuss quality, and undrinkable water. Earth's surface is the as it were territory accessible to the human race. Understanding the forms by which that environment has been made and persistently changed is critical to decide the causes of natural degradation.

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