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Alenkasestr [34]
3 years ago
5

From laboratory measurements, we know that a particular spectral line formed by hydrogen appears at a wavelength of 486.1 nanome

ters (nm). The spectrum of a particular star shows the same hydrogen line appearing at a wavelength of 485.9 nm. What can we conclude?
- The "star" actually is a planet.
- The star is moving away from us.
- The star is getting colder.
- The star is getting hotter.
- The star is moving toward us.
Physics
1 answer:
aksik [14]3 years ago
6 0

Answer:

The star is moving toward us

Explanation:

The wavelength of a distant object changes due to the change in the distance between the observer and the object. This is known as the Doppler effect.

If the wavelength decreases this means that the wavelength in going towards blue which is shorter wavelength. This is known as blue shift. If blue shift occurs then it means that the object is coming closer to the observer.

Hence, the star described here has blue shifted and is moving closer to us.

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Three struts are pinned together at A, B, and C to form a triangular
ZanzabumX [31]

Answer:

a. Fab = 3000 N tension

Fac = 1500 N compression

Fbc = 3000 N compression

b. Aluminum for AB, titanium for AC and BC.

c. Fc = 4000 N

Explanation:

a. Draw free body diagrams of the pins at A and B, assuming that all internal forces are in tension (pulling away from the pin).

Sum of the forces on A in the x direction:

∑F = ma

H − Fab sin 60° = 0

Fab = H / sin 60°

Fab = 2600 / sin 60°

Fab = 3000 N

Sum of the forces on A in the y direction:

∑F = ma

-Fab cos 60° − Fac = 0

Fac = -Fab cos 60°

Fac = -H / tan 60°

Fac = -2600 / tan 60°

Fac = -1500 N (it's negative, so it's actually in compression).

Sum of the forces on B in the x direction:

∑F = ma

Fab cos 30° + Fbc cos 30° = 0

Fbc = -Fab

Fbc = -H / sin 60°

Fbc = -3000 N (it's negative, so it's in compression)

b. AB is in tension, so it should be aluminum.

AC and BC are in compression, so they should be titanium.

c. Draw a free body diagram of the entire triangle ABC.  Assume there is both a horizontal and vertical reaction force at C, and assume they point in the +x and +y directions.

Sum of the forces in the x direction:

∑F = ma

Fcx + H = 0

Fcx = -H

Fcx = -2600 N

Sum of the forces in the y direction:

∑F = ma

Fcy − V = 0

Fcy = V

Fcy = 3000 N

The magnitude of the net force is:

Fc² = Fcx² + Fcy²

Fc² = (-2600 N)² + (3000 N)²

Fc = 4000 N

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3 years ago
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Answer:

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Answer:

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Explanation:

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