Tag: introduction to gravity

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

Let $F _{1}$ be the magnitude of the gravitational force exerted on the Sun by Earth and $F _{2}$ be the magnitude of the force exerted on Earth by the Sun. Then.

  1. $F _{1}$ is much greater than $F _{2}$
  2. $F _{1}$ is slightly greater than $F _{2}$
  3. $F _{1}$ is equal to $F _{2}$
  4. $F _{1}$ is slightly less than $F _{2}$
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction. Therefore, the gravitational force exerted by the Sun on the Earth is equal in magnitude to the force exerted by the Earth on the Sun.

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

------------ is the force of attraction between any two bodies in the universe.

  1. Gravitation

  2. Polarity

  3. Induction

  4. Joule
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Any two objects attract each other with a force $F _g=\dfrac{GMm}{R^2}$ where $G$ is the gravitational constant, $M$ and $m$ the masses of the two bodies and $R$ is the distance along the line joining their centre of mass

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

State whether the given statement is True or False :

All objects attract each other along the line joining their centre of mass.

  1. True

  2. False
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Any two objects attract each other with a force $F _g=\dfrac{GMm}{R^2}$ where $G$ is the gravitational constant, $M$ and $m$ the masses of the two bodies and $R$ is the distance along the line joining their centre of mass

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

The horizontal component of the weight of a body of mass $m$ is

  1. $mg$
  2. $\displaystyle \dfrac{\mathrm{m}\mathrm{g}}{2}$
  3. $0$

  4. Infinity
Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

The force of gravity is the force with which the earth, moon, or other massively large object attracts another object towards itself. By definition, this is the weight of the object. All objects upon earth experience a force of gravity that is directed "downward" towards the center of the earth. So, the horizontal component of the weight of body of mass $m$ will be $0$. $Option$ $C$ is correct.

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

An Earth's satellite is moving in a circular orbit with a uniform speed $v$. If the gravitational force of the Earth suddenly disappears, the satellite will

  1. vanish into outer space.
  2. continue to move with velocity $v$ in original orbit.

  3. fall down with increasing velocity.
  4. fly off tangentially from the orbit with velocity $v$.
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

The satellite revolves around the Earth in a circular orbit when centrifugal force acting outward on the satellite is balanced by the gravitational force of the Earth. Thus, when gravitational force suddenly disappears, then only centrifugal force will be acting and velocity is tangential to the orbit and hence, the satellite will fly off tangentially. It is similar to an object tied with a string, fly off when string suddenly breaks.

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

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

  1. Is the same

  2. Is smaller

  3. Is greater

  4. Varies with its phase
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

Answer is A.

By Newton's Third Law and Newton's Law of Universal gravitation, the gravitational force the Earth exerts on the Moon is exactly the same as the force the Moon exerts on the Earth. 
F (Earth) = F (Moon)
However, the tidal forces are not equal - the Moon exerts a greater tidal force because tidal forces result from a difference in force across the object. Because the Earth has a greater diameter, the difference in the lunar force across the Earth will be greater than the difference that the terrestrial force exerts across the lunar diameter.

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

When a fruit falls from a tree,

  1. only the earth attracts the fruit

  2. both the earth and the fruit attract each other

  3. only the fruit attracts the earth

  4. they repel each other
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

According to the law of physics, the earth attracts the apple and the apple attracts the earth with the same intensity of gravity ( according to 3rd law of dynamics). However the displacement of the two bodies is inversely to their respective masses. The earth attracts the apple i.e it falls on an apple in a billionth of a billionth of a millimeter which is impossible to see.

Thus when a fruit falls from a tree both the earth and the fruit attract each other.