Gravity vs Gravitational Force
Gravity and gravitational force are two concepts that occur when objects with masses are placed in a finite distance from one another. Gravitational force along with electromagnetic force, weak nuclear force, and strong nuclear force build the four fundamental forces of the universe. The collaboration of these four forces is known as the Grand Unified Theory or GUT. The laws of gravitation are very important when it comes to the study of the nature. It plays a vital role in fields such as physics, astrophysics and cosmology. In this article, we are going to discuss what gravity and gravitational force are, and their definitions, similarities, and differences.
Gravity
Gravity is the more common name used for the concept of gravitational field. Gravitational field is a concept of a vector field. The gravitational field is in radial outward direction from the mass. It is measured as GM/r^{2}. G is the universal gravitational constant, having the value of 6.674 x 1011 Newton meter^{2} per kilogram^{2}. This constant is universal, meaning that it remains a fixed value throughout the universe. The gravitational field intensity, also known as gravitational acceleration, is the acceleration of any mass due to the gravitational field. The term gravitational potential, is also a part of the definition for the gravitational field. The gravitational potential is defined as the amount of work required to bring a test mass of one kilogram from infinity to a given point. The gravitational potential is always negative or zero due to the fact that only gravitational attractions exist, and the work done on an object to bring it closer to the mass is always negative. Gravitational field intensity varies in an inverse square relationship with the distance from the mass.
Gravitational Force
Sir Isaac Newton was the first person to formulate gravity. But before him, Johannes Kepler and Galileo Galilei laid out the foundation for him to formulate the gravity. The famous equation F = G M_{1} M_{2} / r^{2} gives the strength of the gravitational force, where M_{1} and M_{2} are point objects and r is the displacement between the two objects. In real life applications, they can be normal objects of any dimension and r is the displacement between the centers of gravity of the objects. The gravitational force is considered as an action at distance. This gives rise to the problem of time gap between interactions. This can be omitted using the gravitational field concept.
What is the difference between Gravity and Gravitational Force?  Gravity or the gravitational field is a vector field, while gravitational force is only a vector.  Gravity lies in the radial direction from the mass, while gravitational force is in the direction of the line connecting the two masses.  Gravitational field requires only one mass, while two masses are required for gravitational force.  Gravitational force is equal to the product of the mass of the test object and the gravitational field intensity.
