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3 years ago

Why does the presence of redshift in spectra of galaxies support an understanding of an expanding universe?

Physics

1 answer:

xenn [34]3 years ago

7 0

Explanation:

Doppler's Effect: If a source is moving towards the observer the frequency of the waves emitted by the source will increase( wavelength will decrease). If the source is moving away from the observer the frequency of the waves emitted by the source will decrease( wavelength will increase). The best example of this is the changing frequency of siren of an ambulance as it moves towards us and then away from us.

The same phenomenon can be observed in celestial objects. When the object will move towards us the wavelength will decrease thus the spectrum will be shifted towards the blue part. This is known as blue shift.

If the object moves away from us the wavelength will increase and thus the spectrum will be shifted towards red part. This is know as Red-shift. This is because red has longer wavelength (620 - 750nm) than blue (450-495nm)

Thus if a galaxy shows us red-shifted spectra it means that it is moving away from us. we have observed this phenomenon in various galaxies thus supporting the expanding universe theory.

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A 240 V circuit has 20 A flowing through it. How much power is it using?

Delvig [45]

Explanation:

P = IV

V = 240

I = 20

P = ?

P = 240 × 20

P = 4800 watts

6 0

2 years ago

What are some properties of transverse waves?

allsm [11]

They send out waves differently and cannot be heard easily

5 0

2 years ago

A NASA satellite has just observed an asteroid that is on a collision course with the Earth. The asteroid has an estimated mass,

Citrus2011 [14]

Answer:

v = 7934.2 m/s

Explanation:

Here the total energy of the Asteroid and the Earth system will remains conserved

So we will have

$-\frac{GMm}{r} + \frac{1}{2}mv_0^2 = -\frac{GMm}{R} + \frac{1}{2}mv^2$

now we know that

$v_0 = 660 m/s$

$M = 5.98 \times 10^{24} kg$

$m = 5 \times 10^9 kg$

$r = 4 \times 10^9 m$

$R = 6.37 \times 10^6 m$

now from above formula

$GMm(\frac{1}{R} - \frac{1}{r}) + \frac{1}{2}mv_0^2 = \frac{1}{2}mv^2$

now we have

$2GM(\frac{1}{R} - \frac{1}{r}) + v_0^2 = v^2$

now plug in all data

$2(6.67 \times 10^{-11})(5.98 \times 10^{24})(\frac{1}{6.37 \times 10^6} - \frac{1}{4 \times 10^9}) + (660)^2 = v^2$

$v = 7934.2 m/s$

5 0

2 years ago

A current cannot produce a magnetic field. *<br><br> True or false

GalinKa [24]

Answer:

False

Explanation:

False, as a magnetic field is generated whenever current travels through a conductor.

An electromagnet consists of a coil of wire wrapped around a bar of iron. The coil and iron bar get magnetized when electric current flows through the wire. An electromagnet also has north and south magnetic poles. The magnetic field is strongest at either pole of the magnet.

8 0

2 years ago

You push a desk with 245 N, but the desk doesn't move due to its friction with the ground. What is the magnitude of the friction

const2013 [10]

If the desk doesn't move, then it's not accelerating.

If it's not accelerating, then the net force on it is zero.

If the net force on it is zero, then any forces on it are balanced.

If there are only two forces on it and they're balanced, then they have equal strengths, and they point in opposite directions.

So the friction on the desk must be equal to your<em> 245N</em> .

7 0

2 years ago