Tag: physics

Questions Related to physics

A family of stars is called a

physics the universe types of galaxies galaxies constellations

  1. galaxy

  2. solar system

  3. universe

  4. whirling havens

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Correct Option: A
Explanation:

The family of a star is called a galaxy.

Cosmic or galactic year is :

physics the universe types of galaxies galaxies constellations

  1. year in which a comet arrives.

  2. period taken by Earth to revolve around the Sun.

  3. year in which total solar eclipse occurs.

  4. period of Sun's revolution around galactic centre.

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Correct Option: D
Explanation:

The galactic year, also known as a cosmic year, is the duration of time required for the solar system to orbit once around the center of the Milky Way galaxy. The length of one orbit range from 225 to 250 million terrestrial years.
The solar system is traveling at an average speed of 828,000 km/h or 514,000 mph within its trajectory around the galactic center, which is about one 1300th of the speed of light speed at which an object could circumnavigate the Earth's equator in 2 minutes and 54 seconds.

Fill in the blank:

Stars in a galaxy are held together by ______.

physics the universe types of galaxies galaxies constellations

  1. light

  2. gravity

  3. radiation

  4. satellites

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Correct Option: B
Explanation:
A galaxy is a large assembly of stars, gas, and dust, held together by the force of gravity.

Solar system revolves around the Milky Way galaxy with the speed of:

physics the universe types of galaxies galaxies constellations

  1. $2.5$ $\text{light years} / s$

  2. $250\ km/s$ 

  3. $250\ \text{light years} / s$

  4. $2.5\ km/s$

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Correct Option: B
Explanation:
The Solar System is travelling at an average speed of $250\ km/s$ on its trajectory around the galactic center.
The Earth belongs to Milky Way galaxy.

Milky Way is moving in local group of galaxies with a speed of:

physics the universe types of galaxies galaxies constellations

  1. $300 \ light\  years \ {s}^{-1}$

  2. $300\  light\  years\ {hr}^{-1}$

  3. $300\ km$ ${s}^{-1}$

  4. $300m$ ${s}^{-1}$

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Correct Option: C
Explanation:
$Milky \ Way$ moves through space within the cluster of galaxies it is a member of. This cluster, in turn, moves through space towards yet another larger cluster of galaxies off in the direction of the constellation $Virgo$. This speed is approximately $300 km/s.$

The total mass of all stars in Milky Way galaxy is about:

physics the universe types of galaxies galaxies constellations

  1. $2\times {10}^{41}\ kg$

  2. $2\times {10}^{31}\ kg$

  3. $2\times {10}^{21}\ kg$ 

  4. $2\times {10}^{11}\ kg$

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Correct Option: A
Explanation:
Total mass of stars in the Milky Way galaxy is about $1.9 \times 10^{41}\ kg$ 
or $=2 \times 10^{41}\ kg$.

The time taken by the Sun to revolve around the centre of our galaxy is:

physics the universe types of galaxies galaxies constellations

  1. 25 million years

  2. 100 million years

  3. 250 million years

  4. 500 million years

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Correct Option: C
Explanation:
The galactic year, also known as a cosmic year, is the duration of time required for the solar system to orbit once around the center of the Milky Way galaxy. 
1 galactic year is almost equal to 250 million years.

Fill in the blank:

If $V$ is the velocity of a receding galaxy and $R$ is the distance of the galaxy from the Earth. Then the relation between $V$ and $R$ is _______ .

physics the universe types of galaxies galaxies constellations

  1. $V \propto \displaystyle\frac{1}{R}$

  2. $V \propto {R}^{2}$

  3. $V \propto R$

  4. $V \propto \displaystyle\frac{1}{{R}^{2}}$

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Correct Option: C
Explanation:

As per Hubble Expansion Law, $H=\displaystyle \frac{V}{R}$,

where $H$ is Hubble constant. 
So, $V \propto R$.

The astronomers have estimated that the universe was formed about _____  years ago.

physics the universe types of galaxies galaxies constellations

  1. 10 million

  2. 15 million

  3. 15 billion

  4. 50 billion

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Correct Option: C
Explanation:

Age of universe is about 15 billion years

The distance between the galaxy Andromeda and Earth is ________ light years.

physics the universe types of galaxies galaxies constellations

  1. $2 \times {10}^{6}$

  2. $3 \times {10}^{8}$

  3. $22 \times {10}^{16}$

  4. $12 \times {10}^{8}$

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Correct Option: A
Explanation:

Distance between galaxy Andromeda and Earth is $2\times { 10 }^{ 6 }$

Ans : $2\times { 10 }^{ 6 }$