Tag: universe and space

Questions Related to universe and space

State whether true or false.
Gravitational forces can also be repulsive like that of electrostatic forces.
physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. True

  2. False

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Correct Option: B
Explanation:

Gravitational force, $F=\cfrac { G{ M } _{ 1 }{ M } _{ 2 } }{ { R }^{ 2 } } $

Now the mass of the objects can not be opposite (i.e., mass cannot be negative), thus, the nature of the force cannot be repulsive like that of electrostatic force.

The mass of the moon is about $1.2$% of the mass of the earth. Compared to the gravitational force that earth exerts on the moon, the gravitational force the moon exerts on earth :

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. is the same

  2. is smaller

  3. is greater

  4. Varies with its plane

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Correct Option: A
Explanation:

The gravitation force of attraction between two bodies is given by, $F=-\dfrac{Gm _1m _2}{r^2}$ where $G=$ gravitational constant, $m _1,m _2$  be the masses of bodies and $r$ be the distance between them.

As the force depends on the product of masses and distance between them, so same force will exert on each other.

If E, M, J and G, respectively, denote energy, mass, angular momentum, and gravitational constant, then $EJ^2 / M^5G^2$ has the dimensions of

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. Time

  2. Angle

  3. Mass

  4. Length

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Correct Option: B
Explanation:

$E=ML^2T^{-2}\ M+ML^0T^0\ G=M^{-1}L^3T^{-2}\ J=ML^2T^{-1}$

$EJ^2/M^5G^2=Ml^2T^{-2}\times M^2L^2T^{-1}$
$=M^5\times M^{-2}\times L^{-6}T^{-4}\ =M^0L^0T^0$

Choose the correct statement:

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. The dimensional formula for $G$ is ${M}^{-1}{L}^{3}{T}^{-2}$

  2. $G$ is independent of medium

  3. $F=G\cfrac{{m} _{1}{m} _{2}}{{r}^{2}}$

  4. All of the above

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Correct Option: D

To double the orbital speed V and halve the angular velocity $\omega $, The centripetal acceleration of a revolving body:

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. Is quadrupled

  2. Remains Unchanged

  3. Is halved

  4. Is doubled

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Correct Option: A

The force of attraction between two unit point masses separated by a unit distance is called

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. Gravitational potential

  2. Acceleration due to gravity.

  3. Gravitational field

  4. Universal gravitational constant.

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Correct Option: D
Explanation:

Universal gravitational constant is the force of attraction between two bodies of unit mass and at a unit distance from each other.

In the relation F= $\dfrac{G M m}{r^{2}}$, the quantity G

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. depends on the value of g at the place of observation.

  2. is used only when the earth is one of the two masses.

  3. is greatest at the surface of the earth.

  4. is universal constant in nature.

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Correct Option: D
Explanation:

G is the universal gravitational constant which remains constant irrespective of the place and time. G is the force of attraction between two bodies of unit mass and unit distance apart.

A body of mass $5\ kg$ is cut into two parts of masses (a) $\dfrac {m}{4}; \dfrac {3m}{4}$ (b) $\dfrac {m}{7}; \dfrac {5m}{7}$ (c) $\dfrac {m}{2}; \dfrac {m}{2}$ (d) $\dfrac {m}{5}; \dfrac {4m}{5}$. When these two pieces are kept apart by certain distance; In which case the gravitational force acting is maximum?

physics universe and space heliocentric model introduction to gravitation introduction to gravity

  1. In case a

  2. In case C

  3. In case d

  4. In case b

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Correct Option: B
Explanation:

Gravitation force between two masses is given by $F=\cfrac { G{ m } _{ 1 }{ m } _{ 2 } }{ { r }^{ 2 } } $

In case I:${ F } _{ 1 }=\cfrac { G\cfrac { m }{ 4 } .\cfrac { 3m }{ 4 }  }{ { r }^{ 2 } } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } \times \cfrac { 1 }{ 16 } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } \times 0.0625$
In case II: ${ F } _{ 2 }=\cfrac { G\cfrac { m }{ 7 } .\cfrac { 5m }{ 7 }  }{ { r }^{ 2 } } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } \times \cfrac { 5 }{ 7 } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } \times 0.714$
In case III: ${ F } _{ 3 }=\cfrac { G\cfrac { m }{ 2 } .\cfrac { m }{ 2 }  }{ { r }^{ 2 } } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } .\cfrac { 1 }{ 4 } =\cfrac { G{ m }^{ 2 } }{ { r }^{ 2 } } \times 0.25$
${ F } _{ 2 }$ is maximum.

When the flow parameters of any given instant remain same at every point, then flow is said to be

social science universe and space the big bang and the early development of the universe origin of universe evolution of the universe

  1. laminar

  2. steady state

  3. turbulent

  4. quasistatic

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Correct Option: B
Explanation:

When the flow parameters (like pressure, velocity etc) doesn't change w.r.t time i.e remains constant through out the time period, then this state is called as STEADY STATE.

Universe is:

social science universe and space the big bang and the early development of the universe origin of universe evolution of the universe

  1. a dialect between two people

  2. the study of light propagation between Sun and the Earth

  3. the vast surrounding space which includes everything that exists from the Earth to the most distant parts of space that one can possibly see

  4. the solar system

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Correct Option: C
Explanation:

The universe is the vast surrounding space which includes everything that exists from the Earth to the most distant parts of space that one can possibly see.