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emmainna [20.7K]
3 years ago
7

Which one of the statements below is true about mechanical waves?

Physics
1 answer:
ratelena [41]3 years ago
3 0

Answer:

D) Mechanical waves require a medium for transmission (wire, air, etc.) as opposed to electromagnetic which travel through empty space - light, radio, etc.)

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How much heat must be removed from 456 g of water at 25.0°C to change it into ice at - 10.0°C?
Svet_ta [14]

Answer:

229,098.96 J

Explanation:

mass of water (m) = 456 g = 0.456 kg

initial temperature (T) = 25 degrees

final temperature (t) = - 10 degrees

specific heat of ice = 2090 J/kg

latent heat of fusion =33.5 x 10^(4) J/kg

specific heat of water = 4186 J/kg

for the water to be converted to ice it must undergo three stages:

  • the water must cool from 25 degrees to 0 degrees, and the heat removed would be Q = m x specific heat of water x change in temp

        Q = 0.456 x 4186 x (25 - (-10)) = 66808.56 J

  • the water must freeze at 0 degrees, and the heat removed would be Q = m x specific heat of fusion x change in temp

         Q = 0.456 x 33.5 x 10^(4) = 152760 J

  • the water must cool further to -10 degrees from 0 degrees, and the heat removed would be Q = m x specific heat of ice x change in temp

        Q = 0.456 x 2090 x (0 - (-10)) = 9530.4 J

The quantity of heat removed from all three stages would be added to get the total heat removed.

Q total = 66,808.56 + 152,760 + 9,530.4 = 229,098.96 J

6 0
3 years ago
A disk 7.90 cm in radius rotates at a constant rate of 1 190 rev/min about its central axis. (a) Determine its angular speed. 12
Tanya [424]

Answer:

124.62\ \text{rad/s}

3.71\ \text{m/s}

1.23\ \text{km/s}^2

20.28\ \text{m}

Explanation:

r = Radius of disk = 7.9 cm

N = Number of revolution per minute = 1190 rev/minute

Angular speed is given by

\omega=N\dfrac{2\pi}{60}\\\Rightarrow \omega=1190\times \dfrac{2\pi}{60}\\\Rightarrow \omega=124.62\ \text{rad/s}

The angular speed is 124.62\ \text{rad/s}

r = 2.98 cm

Tangential speed is given by

v=r\omega\\\Rightarrow v=2.98\times 10^{-2}\times 124.62\\\Rightarrow v=3.71\ \text{m/s}

Tangential speed at the required point is 3.71\ \text{m/s}

Radial acceleration is given by

a=\omega^2r\\\Rightarrow a=124.62^2\times 7.9\times 10^{-2}\\\Rightarrow a=1226.88\approx 1.23\ \text{km/s}^2

The radial acceleration is 1.23\ \text{km/s}^2.

t = Time = 2.06 s

Distance traveled is given by

d=vt\\\Rightarrow d=\omega rt\\\Rightarrow d=124.62\times 7.9\times 10^{-2}\times 2.06\\\Rightarrow d=20.28\ \text{m}

The total distance a point on the rim moves in the required time is 20.28\ \text{m}.

8 0
3 years ago
Is Environmental Nature or Nurture?
erma4kov [3.2K]
ANSWER: NATURE




EXPLAINTION:
4 0
3 years ago
A contact force exists between two interacting objects that physically contact each other. a non-contact force exists when two i
Murrr4er [49]
True.

A contact force is a force between two objects that are physically in contact with each other: an example of a contact force is the normal reaction of a table supporting a book.

A non-contact force is a force between two objects that are not physically in contact with each other: an example of non-contact force is the gravitational attraction between the Earth and the Moon.
4 0
3 years ago
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lorasvet [3.4K]

Answer:

a) The plasma membrane is called a selectively permeable membrane as it permits the movement of only certain molecules in and out of the cells. ... It allows hydrophobic molecules and small polar molecules diffuse through the lipid layer, but does not allow ions and large polar molecules cannot diffuse through the membrane

b) Plastids are present in the cells of plants. They are characterised by the presence of pigments. ... Chloroplasts contain chlorophyll and carotenoid pigments responsible for capturing the light energy that is necessary for photosynthesis. The chloroplasts are therefore known as the kitchen of the cell.

c) Lysosomes are known as the suicidal bag of the cell because it is capable of destroying its own cell in which it is present. It contains many hydrolytic enzymes which are responsible for the destruction process. This happens when either the cell is aged or gets infected by foreign agents like any bacteria or virus.

d) Mitochondria are often called the “powerhouses” or “energy factories” of a cell because they are responsible for making adenosine triphosphate (ATP), the cell's main energy-carrying molecule. ... In mitochondria, this process uses oxygen and produces carbon dioxide as a waste product.

e) In Hydra, the cells are arranged in two germinal layers—outer ectoderm and inner endoderm. Between these two layers is a layer of undifferentiated cells called mesoglea. Such kind of pattern of embryonic layers is seen in diploblastic animals. Hence, Hydra is a diploblastic animal.

<em>WAS</em><em> </em><em>THIS</em><em> </em><em>ANSWER</em><em> </em><em>HELPFUL</em><em> </em><em>?</em>

MARK ME AS A BRAINLIEST

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3 years ago
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