1.4:
Newton’s Law of Gravitational Attraction
Newton's law of gravitational attraction states that when two particles of masses m1 and m2 are separated by distance r, they attract each other with equal and opposite forces.
The attraction force acts along the line joining the particles and varies directly as the product of their masses and inversely as the square of the distance between them, where G is the universal constant known as the gravitational constant.
The gravitational attraction force exerted by the Earth on an object is the object's weight. It is the product of the object's mass and acceleration due to gravity, expressed in newton.
Gravity separators, drop hammers, and gravity conveyors are a few mechanical tools that work on the principle of Newton's law of gravitation.
Consider the drop hammer forging process. Here, the hammer of a specific weight is raised to a certain height and then allowed to fall freely.
Since the Earth has a strong gravitational pull, the hammer always falls. The force created by this fall gives the required shape to the workpieces.
1.4:
Newton’s Law of Gravitational Attraction
Sir Isaac Newton established the universality of the law of gravitational attraction based on empirical evidence and inductive reasoning. He published his work in Philosophiae Naturalis Principia Mathematica ("the Principia") on July 5, 1687.
Newton's law of gravitational attraction is a fundamental law of physics that governs the attraction between objects. It states that the magnitude of the gravitational force between any two objects is proportional to their masses and inversely proportional to the square of their distance from one another.
Gravity is stronger between objects with greater mass. Every pair of bodies experiences gravitational forces. One of the most ubiquitous applications of this law is our understanding of the motion of the planets in the solar system. The gravitational force between the planets and the sun is responsible for their motion around the sun. It also explains phenomena such as tides caused by the moon's gravitational force on the Earth.
Another example where this law is used is in the design of roller coasters. Roller coaster carts are set in motion with a chain lift hill, which provides the initial force to move the cart up the first steep hill. Once at the top, gravity pulls the cart down the track through a series of turns, loops, and drops.
The universal law of gravitation is significant because it has been successful in explaining many phenomena, such as how different objects in the macroscopic universe affect each other, how gravity is accountable for a body's weight and holds us on the ground, how the moon moves around the Earth, how planetary motion happens, the generation of tidal forces, and so forth.
Suggested Reading
- Hibbeler, R.C. (2016). Engineering Mechanics ‒ Statics and Dynamics. Hoboken, New Jersey: Pearson Prentice Hall. pp 7
- Beer, F.P.; Johnston, E.R.; Mazurek, D.F; Cromwell, P.J. and Self, B.P. (2019). Vector Mechanics for Engineers ‒ Statics and Dynamics. New York: McGraw-Hill. pp 4 and 5
- Meriam, J.L.; Kraige, L.G. and Bolton, J.N. (2020). Engineering Mechanics ‒ Statics. Hoboken, New Jersey: John Wiley. pp 7 and 8