Question

At which height is gravity zero?

Answer 1

Hint: Gravitational force is one of the fundamental forces. It can be defined as the fundamental force which causes attraction between all things with mass or energy. This force is the weakest force among the four fundamental forces.


Formula used:
The Newton’s universal gravitational law,
     \[F = G\dfrac{{{m_1}{m_2}}}{{{r^2}}}\]
Where, \[F\] - force
     \[G\] - gravitational constant (\[6.6743{\rm{x1}}{{\rm{0}}^{ - 11}}{m^3}k{g^{ - 1}}{s^{ - 2}}\])
     \[{m_1}\]- mass of the first object
     \[{m_2}\] - mass of the second object
       \[r\] - distance between the two masses



Complete answer:
Even though gravitational force is the weakest force, it is present everywhere in the universe and every object with mass or energy tends to be acted upon by gravitational force in its course of action. Hence, gravity cannot be zero at any height except maybe at infinity.
According to Newton’s universal gravitational law, the force of attraction is directly proportional to the product of the masses of the two objects and inversely proportional to the square root of the distance between them, which is expressed as,
\[F = G\dfrac{{{m_1}{m_2}}}{{{r^2}}}\]
Based on the above formula, gravity can never be zero, even if we move out of the surface of earth because the force is inversely proportional to the square of the distance between the two masses, hence, the force can get weaker as we further away from the earth’s surface, but it can never be zero.
According to Newton’s law of gravity, only when the distance between the two masses is infinite, then the effect of gravitational force can be zero.


Note: The gravitational force varies inversely with the square of distance between two bodies, hence it will only get weaker as the distance increases. The gravitational constant (G) is introduced as the proportionality constant for Newton’s universal law of gravitation.