Gravity is a fundamental phenomenon that brings everything in the universe together, and universal gravitation describes the way that every object attracts every other object in the universe. Gravitation depends on mass and distance.
The greater an object’s mass, the more gravity the object has—meaning that other objects are pulled more strongly toward it. The shorter the distance between two objects, the greater the gravitational pull.
This proportionality of gravitation is infinite—meaning that no matter how small or how far away an object is, it is still acting and being acted upon by gravitation.
- Gravitation and weight are not the same. The weight of an object is only a relative measurement of how gravity is acting on that object at a given time and in a given frame of reference.
- Because gravitation is universal, it is impossible to achieve a state of zero gravity. Astronauts or rockets in outer space still experience gravity, only the pull from the earth is smaller due to the greater distance.
- Gravity affects anything with mass or energy, including stars, planets, buildings, people, air, and even light.
- Gravitation is constant, which means that everything in the universe depends on gravity in order to exist. Without gravity, nothing could function.
- The law of universal gravitation is the product of Sir Isaac Newton, who studied the effects of gravity during the seventeenth century.
- The gravitational pull of the moon acting on the ocean is what causes tides. This is perhaps the most apparent evidence for universal gravitation between celestial bodies.
- While it is easy to imagine gravity as a force, it is actually the bending and stretching of space-time, the fabric of the universe, that feels like a force.
- Phenomenon: A fact or event that is observable.
- Mass: A property of a physical body that is the measurement of its resistance to acceleration.
- Weight: A relative measurement of the pull of gravity acting on an object.
Questions and Answers
Question: Would a person’s weight be different at the equator than it would be at the North Pole?
Answer: Yes. Because the earth is slightly wider near the equator, the distance between the person and the center of the earth would be greater. This would result in a smaller pull of gravity and a lighter weight, but the difference would be negligible.
Watch this video to learn more about gravity and universal gravitation.