Question

Under the action which force does water flow from an open tap towards ground
A.Electrostatic force
B.Magnetic force
C.Gravitational Force
D.None of the above

Answer 1

Any object on the earth has a tendency to move downwards towards the earth because of gravity. This force, exerted on the object by the earth is known as force of gravity or gravitational force. It operates between two bodies and it is attractive in nature
Formula: $F=G\dfrac{{{m}_{1}}{{m}_{2}}}{{{r}^{2}}}$

Complete answer:
When an object falls downwards, towards the earth gravitational force acts on it. We know that, gravitational force acting between two bodies of mass ${{m}_{1}}$and ${{m}_{2}}$ separated by a distance ‘r’ is given by
$F=G\dfrac{{{m}_{1}}{{m}_{2}}}{{{r}^{2}}}$
Here, G is known as gravitational constant
Therefore, the force acting between a body and earth is given by
$F=G\dfrac{{{M}_{E}}m}{{{R}_{E}}^{2}}$
This force is attractive in nature.
Where ${{M}_{E}}$denotes mass of the earth and ${{R}_{E}}$denotes the radius of the earth
m is the mass of the body. This force is much larger than any other force acting on flowing water. So, when the tap is opened earth attracts water towards itself by force F.

Hence, Option (C) is correct.

Additional information:
Gravitation is a natural phenomenon by which every particle of the universe having mass attracts every other particle of another mass. Some of the examples are: The force that keeps the Earth and all of the planets in the proper position in their orbits around the sun, the force which the moon exerts and causes tides in the ocean. Gravitational force is explained by ‘The law of gravitation’ also known as Newton’s Law of Universal Gravitation.
Electrostatic force is an attractive or repulsive force which acts between stationary electrically charged particles. The electric force between a stationary charged body is conventionally known as the electrostatic force or Coulomb's force. So the Electrostatic force acting between two charges ${{q}_{1}}$ and ${{q}_{2}}$ and the distance between them is ‘r’ is given by
$F=k\dfrac{{{q}_{1}}{{q}_{2}}}{{{r}^{2}}}$
Here, k is Coulomb's constant
Magnetic force is an attractive or repulsive force which arises between electrically charged particles because of their motion. Magnetic force is given by the formula
$F=qvB\sin \theta$

Note:
Gravitational force is attracting in nature always and it follows inverse square law which implies that force is inversely proportional to the square of the distance ‘r’ between their masses $F\alpha \dfrac{1}{{{r}^{2}}}$ and directly proportional to the product of their masses.
Some of the constant values that one must remember
Gravitational constant $G=6.674\times {{10}^{-11}}{{m}^{3}}k{{g}^{-1}}{{s}^{-2}}$
Mass of the earth ${{M}_{E}}=5.972\times {{10}^{24}}kg$
Radius of earth ${{R}_{E}}=6,371km$
Coulomb's constant $k=\dfrac{1}{4\pi {{\xi }_{o}}}=8.9875\times {{10}^{9}}N{{m}^{2}}{{C}^{-2}}$
Charge on a particle $e=1.602\times {{10}^{-19}}C$