Tag: representing a gravitational field

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Questions Related to representing a gravitational field

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

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?

  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
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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.)

  1. $\sqrt{2gR}$
  2. $\sqrt{gR}$
  3. $\sqrt{gR/2}$
  4. $\sqrt{gR}\left(\sqrt{2}-1\right)$
Reveal answer Fill a bubble to check yourself
D Correct answer
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
$v^{\prime}=v=\sqrt{\cfrac{2GM}{R}}-\sqrt{\cfrac{GM}{R}}\ \quad=\sqrt{2gR}-\sqrt{gR}=\sqrt{gR}(\sqrt2-1)$

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

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

  1. $10 Dynes$
  2. $10^2 Dynes$
  3. $10^5 Dynes$
  4. $10^6 Dynes$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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

  1. gravitational intensity

  2. electric intensity

  3. magnetic intensity

  4. gravitational constant
Reveal answer Fill a bubble to check yourself
A Correct answer
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 $ 

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

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

  1. $10^3:1$

  2. infinity

  3. zero
  4. $10^2:1$
Reveal answer Fill a bubble to check yourself
D Correct answer
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 $ 

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

Which of the following represents the unit for gravitational intensity?

  1. N
  2. $kgm^{-2}$
  3. $Nkg^{-1}$
  4. $ms^{-3}$
Reveal answer Fill a bubble to check yourself
C Correct answer
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 $ 

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

The speed at which the gravitational field propagates is

  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
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

The unit of (V) Gravitational Potential is

  1. $\dfrac{\text{Joule}}{kg}$
  2. $\text{Joule}$
  3. $\dfrac{\text{Joule}}{s}$
  4. $\dfrac{kg}{\text{Joule}}$
Reveal answer Fill a bubble to check yourself
A Correct answer
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.