Tag: representing a gravitational field

Questions Related to representing a gravitational field

Electrical, as well as gravitational affects, can be thought to be caused by fields. Which of the following is true of an electrical or gravitational field?

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. The field concept is often used to describe contact forces

  2. Gravitational or electric field does not exist in the space around an object

  3. Fields are useful for understanding forces acting through a distance

  4. There is no way to verify the existence of a force field since it is just a concept

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Correct Option: C
Explanation:

In physics, concept of field is a model used to explain the influence that a massive body or charged particle extends into the space around itself, producing a force on another massive body or charged body placed in space. Thus, concept of field is used to explain gravitational and electrostatic phenomena.

A satellite is revolving in a circular orbit at a height $'h'$ from the earth's surface (radius of earth $R$;$h\ <\ <\ R$). The minimum increase in its orbital velocity required, so that the satellite could escape from the earth's gravitational field, is close to:(Neglect the effect of atmosphere.)

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. $\sqrt{2gR}$

  2. $\sqrt{gR}$

  3. $\sqrt{gR/2}$

  4. $\sqrt{gR}\left(\sqrt{2}-1\right)$

Show answer
Correct Option: D
Explanation:

height$=h$

No, the given formula,
Orbital velocity
$v=\cfrac{GM}{R+h}=\cfrac{GM}{R}$ as $h<<R$
Velocity required to escape
$\cfrac{1}{2}mv^{\prime 2}=\cfrac{GMm}{R+h}\v^{\prime}=\cfrac{2GM}{R+h}=\cfrac{2GM}{R}(h<<R)$
$\therefore$ Increase in velocity
$v^{\prime}=v=\sqrt{\cfrac{2GM}{R}}-\sqrt{\cfrac{GM}{R}}\ \quad=\sqrt{2gR}-\sqrt{gR}=\sqrt{gR}(\sqrt2-1)$

A force of 10 N of gravitational force in CGS units is  represented as

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. $10 Dynes$

  2. $10^2 Dynes$

  3. $10^5 Dynes$

  4. $10^6 Dynes$

Show answer
Correct Option: A
Explanation:

A force of 10 N of gravittional force in CGS units is represented by 10 Dynes.

Dyne is a CGS unit of force which accelerates a mass of one gram at the rate of one centimeter per second.

The presence of gravitational field is required for the heat transfer by

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. $conduction$

  2. $striring\ of\ liquids$

  3. $natural\ convection$

  4. $radiation$

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Correct Option: A
Explanation:

Presence of gravitational field is required for heat transfer by conduction.

The force experienced by a unit mass at a point in the gravitational field is called its

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. gravitational intensity

  2. electric intensity

  3. magnetic intensity

  4. gravitational constant

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Correct Option: A
Explanation:

The force experienced by a $unit $ mass at a point in the gravitational field $=F _g=mg=1\times g=g $ $ Newton $


We know that $g$ is called as gravitational intensity 

Hence correct answer is option $A $ 

The ratio of SI units to CGS of the gravitational intensity is

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. $10^3:1$

  2. infinity

  3. zero

  4. $10^2:1$

Show answer
Correct Option: D
Explanation:

Gravitational intensity is nothing but the acceleration due to gravity(g)

SI unit of g is $m/s^2=100cm/s^2$
But CGS unit of g is $cm/s^2$ 
So SI unit:CGS unit $=100:1$ 

Hence correct answer is option $D $ 

Which of the following represents the unit for gravitational intensity?

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. N

  2. $kgm^{-2}$

  3. $Nkg^{-1}$

  4. $ms^{-3}$

Show answer
Correct Option: C
Explanation:

Gravitational intensity is nothing but the acceleration due to gravity $=g=F _g/m$


Now we know that the SI unit of $F _g$ is $Newton(N) $ and that of $m$ is $kg$
So SI unit of $g=N/kg=Nkg^{-1}$ or $m/s^2$ 

Hence correct answer is option $C $ 

The space in which a body experiences a force by virtue of its mass, is called a/an

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. magnetic field

  2. electric field

  3. gravitational field

  4. none of these

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Correct Option: C
Explanation:

The region of space surrounding a body in which another body experiences a force of gravitational attraction is called a gravitational field.

The speed at which the gravitational field propagates is

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. Equal to the speed of light in vacuum

  2. Less than the speed of light in vacuum

  3. More than the speed of light in vacuum

  4. Either less or more than the speed of light in

    vacuum

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Correct Option: A
Explanation:

The speed of gravitational waves in the general theory of relativity is equal to the speed of light in vacuum.

The unit of (V) Gravitational Potential is

physics gravitational fields representing a gravitational field gravitational field circular motion and gravitation

  1. $\dfrac{\text{Joule}}{kg}$

  2. $\text{Joule}$

  3. $\dfrac{\text{Joule}}{s}$

  4. $\dfrac{kg}{\text{Joule}}$

Show answer
Correct Option: A
Explanation:

Gravitational potential is defined as the Gravitational energy per unit mass of the object on the planet. Unit of energy is always joule in SI units. Hence that of potential will be Joule/kg.