Question

Which of the following statements regarding gravitational force existing between two bodies is TRUE?

• A. First body exerts attractive force on second body while second body exerts repulsive force on first body.
• B. The gravitational force is zero when they are kept in vacuum.
• C. Force exerted by first body on second is not equal to the force exerted by second body on first.
• D. Force exerted by first body on second body is equal to the force exerted by second body on first.

Answer 1

The correct option is D

Force exerted by first body on second body is equal to the force exerted by second body on first.

Gravity (or gravitation): The universal force of attraction acting between all matters.

Newton's law of gravitation:

1. Every particle in the universe attracts every other particle with a force, which is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
2. If two bodies with mass $m_1$and $m_2$ where $r$ is the distance between two masses, then gravitational force is given by $F\propto \frac{m_1{m}_2}{r^2}\Rightarrow F=G\frac{m_1{m}_2}{r^2}$
3. According to Newton's law of gravitation, there is no role of medium between the masses. So there is no effect of the vacuum on the gravitational force.
4. Both the masses attract each other by the gravitational force and both the masses apply the same force on each other that is $F_1=F_2$.
5. Force exerted by the first body on the second body is equal to the force exerted by the second body on the first.

Hence, option (D) is correct.