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3 years ago

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Two people are talking through a thick wall, 3 meters high, between them. This fact can best be explained by the phenomenon of A

) diffraction. B) refraction. C) reflection. D) polarization. E) none of the above

1 answer:

dezoksy [38]3 years ago

6 0

The answer is Ai just took it

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A student heats a piece of aluminum, with specific heat 0.900 J/gºC, in

tankabanditka [31]

Answer:

my bad i need points good luck

Explanation:

adawd

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3 years ago

An object is thrown upward from the edge of a tall building as with a velocity of 10m/s. where will the object be 3s after it is

KonstantinChe [14]

20 m is the answer, hope that helps

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3 years ago

In hydrogen, the transition from level 2 to level 1 has a rest wavelength of 121.6 nm.1).Find the speed for a star in which this

soldier1979 [14.2K]

Answer:

1). $v = - 2960526m/s$

2). Toward us

3). $v = - 493421m/s$

4). Toward us

5). $v = 1480263m/s$

6). Away from us

7). $v = 3207236m/s$

8). Away from us

Explanation:

Spectral lines will be shifted to the blue part of the spectrum if the source of the observed light is moving toward the observer, or to the red part of the spectrum when it is moving away from the observer (that is known as the Doppler effect).

The wavelength at rest is 121.6 nm ( $\lambda_{0} = 121.6nm$ )

$Redshift: \lambda_{measured} > \lambda_{0}$

$Blueshift: \lambda_{measured} < \lambda_{0}$

Then, for this particular case it is gotten:

Star 1: $\lambda_{measured} = 120.4nm$

Star 2: $\lambda_{measured} = 121.4nm$

Star 3: $\lambda_{measured} = 122.2nm$

Star 4: $\lambda_{measured} = 122.9nm$

Star 1:

$Blueshift: 120.4nm < 121.6nm$

Toward us

Star 2:

$Blueshift: 121.4nm < 121.6nm$

Toward us

Star 3:

$Redshift: 122.2nm > 121.6nm$

Away from us

Star 4:

$Redshift: 122.9nm > 121.6nm$

Away from us

Due to that shift the velocity of the star can be determine by means of Doppler velocity.

$v = c\frac{\Delta \lambda}{\lambda_{0}}$ (1)

Where $\Delta \lambda$ is the wavelength shift, $\lambda_{0}$ is the wavelength at rest, v is the velocity of the source and c is the speed of light.

$v = c(\frac{\lambda_{measured}- \lambda_{0}}{\lambda_{0}})$ (2)

<em>Case for star 1 $\lambda_{measured} = 120.4 nm$ :</em>

<em></em>

$v = (3x10^{8}m/s)(\frac{120.4nm-121.6nm}{121.6nm})$

$v = - 2960526m/s$

Notice that the negative velocity means that is approaching to the observer.

<em>Case for star 2 $\lambda_{measured} = 121.4 nm$ :</em>

$v = (3x10^{8}m/s)(\frac{121.4nm-121.6nm}{121.6nm})$

$v = - 493421m/s$

<em>Case for star 3 $\lambda_{measured} = 122.2 nm$ :</em>

$v = (3x10^{8}m/s)(\frac{122.2nm-121.6nm}{121.6nm})$

$v = 1480263m/s$

<em>Case for star 4 $\lambda_{measured} = 122.9 nm$ :</em>

$v = (3x10^{8}m/s)(\frac{122.9nm-121.6nm}{121.6nm})$

$v = 3207236m/s$

4 0

3 years ago

Indicate whether each of the following statements is true or false. In a coal-fired power plant, chemical energy is first conver

denis23 [38]

Answer:

1. In a coal-fired power plant, chemical energy is first converted to thermal energy. TRUE.

The chemical energy in the coal is converted to thermal energy when the coal is burnt to produce steam.

2. In a coal-fired power plant, approximately 2/5 of original energy in the coal is lost to heat. FALSE.

Approximately 3/5 of the original energy is lost not 2/5 so this statement is false.

3. The molecules in cold air move faster than in hot air. FALSE.

Molecules with more heat move faster than molecules with less. Molecules in cold air therefore, will move slower than molecules in hot air.

6 0

3 years ago

A woman takes her dog Rover for a walk on a leash. To get the little pooch moving forward, she pulls on the leash with a force o

stepladder [879]

<u>Answer:</u>

15.97 N force is tending to pull Rover forward

<u>Explanation:</u>

The woman pulls on the leash with a force of 20.0 N at an angle of 37° above the horizontal. The arrangement is shown in the given figure,

We nee to find the pulling force P. The 20.0 N force has two components, 20.0 cos 37 in horizontal direction and 20.0 sin 37 in vertical direction.

The horizontal component is equal to pulling force P, which will pull Rover forward/

So, P = 20.0 cos 37 = 15.97 N

15.97 N force is tending to pull Rover forward.

4 0

3 years ago