Question

___________ is the force of attraction between any two bodies in the universe.
A. Gravitation
B. Polarity
C. Induction
D. Joule

Answer 1

Hint: According to Newton’s law of gravitation, there is a force of attraction in between each and every body of mass in the universe. This force of attraction depends directly on the masses of the two bodies and inversely upon the square of the distance between their centers. This force is known as the gravitational force.

Formula used:
The gravitational force of attraction $\left( \overrightarrow{{{F}_{g}}} \right)$ exerted by a mass $M$ on another mass $m$ is given by
$\overrightarrow{{{F}_{g}}}=\dfrac{GMm}{{{r}^{2}}}\widehat{{{r}_{21}}}$
where $r$ is the distance between their centers and $\widehat{{{r}_{21}}}$ is a unit vector in the direction of the line joining mass $M$ with mass $m$ and originating from mass $m$ and $G$ is the universal gravitational constant equal to $6.67\times {{10}^{-11}}{{m}^{3}}k{{g}^{-1}}{{s}^{-2}}$.

Complete step by step answer:
Newton in his famous law of gravitation stated that each body in this universe exerts a force of attraction on all other bodies. This force of attraction is known as the gravitational force. It was found that this force of attraction depends directly on the masses of the two bodies and inversely upon the square of the distance between their centers.
Hence,
the gravitational force of attraction $\left( \overrightarrow{{{F}_{g}}} \right)$ exerted by a mass $M$ on another mass $m$ is given by
$\overrightarrow{{{F}_{g}}}=\dfrac{GMm}{{{r}^{2}}}\widehat{{{r}_{21}}}$
where $r$ is the distance between their centers and $\widehat{{{r}_{21}}}$ is a unit vector in the direction of the line joining mass $M$ with mass $m$ and originating from mass $m$ and $G$ is the universal gravitational constant equal to $6.67\times {{10}^{-11}}{{m}^{3}}k{{g}^{-1}}{{s}^{-2}}$.
Therefore, the correct option is A) Gravitation.

Note: Students often think that the force of gravitation only exists upon the earth, since it is the gravitational force that we are most familiar with in our everyday life. It is very non-intuitive for students that every object attracts each and every object. However, they must understand that they exert a force of gravitation on a book lying nearby and the book exerts a force upon them. It is just that the magnitude of the force is very small as the masses of the book and human are relatively small and therefore, according to the formula, the magnitude of the force is also very small to be felt properly.