Definition:
The universal gravitation constant, denoted by G, is a fundamental constant in physics that represents the strength of the gravitational force between two objects. It appears in Isaac Newton's law of universal gravitation, which states that every particle in the universe attracts every other particle with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.

Explanation:
The universal gravitation constant plays a crucial role in understanding the behavior of gravitational forces. Here is a detailed explanation of its significance and how it is used in calculations:

Newton's Law of Universal Gravitation:
According to Newton's law of universal gravitation, the gravitational force (F) between two objects is given by the equation:

F = G * (m1 * m2) / r^2

Where:
- F is the gravitational force between the two objects.
- G is the universal gravitation constant.
- m1 and m2 are the masses of the two objects.
- r is the distance between the centers of the two objects.

Determining the Strength of Gravitational Force:
The universal gravitation constant, G, determines the strength of the gravitational force. It is a fixed value that is the same throughout the universe. The value of G is approximately 6.67430 × 10^-11 N m^2/kg^2.

Importance in Calculations:
The value of G allows us to calculate the gravitational force between any two objects in the universe. By knowing the masses of the objects and the distance between them, we can use Newton's law of universal gravitation to find the force of attraction between them.

Relationship with Mass and Distance:
The universal gravitation constant shows that the force of gravity is directly proportional to the product of the masses of the objects and inversely proportional to the square of the distance between them. This means that:
- Increasing the mass of one or both objects will increase the gravitational force.
- Increasing the distance between the objects will decrease the gravitational force.

Experimental Determination:
The value of G was determined through careful experiments conducted by Henry Cavendish in the late 18th century. Cavendish used a torsion balance to measure the small gravitational force between two lead spheres and determined the value of G by comparing it with the known masses and distances.

Conclusion:
The universal gravitation constant, G, is a fundamental constant that represents the strength of the gravitational force between two objects. It is used in calculations to determine the force of gravity and plays a crucial role in understanding the behavior of gravitational forces in the universe.

According to universal law of gravitation every body in the universe attracts every other body
further, force is directly proportional to the product of the masses.