Gravitation and gravity

The terms gravity and gravitation are often used to explain the same thing, but there is a definite difference between the two.

Gravitation is the attractive force existing between any two objects that have mass. The force of gravitation pulls objects together.

Gravity is the gravitational force that occurs between the earth and other bodies. Gravity is the force acting to pull objects toward the earth.

Since gravitational force is happening to all matter (objects) in the universe, from the largest galaxies down to the smallest atoms, it is often called universal gravitation. Sir Isaac Newton was the first to fully recognize that the force holding any object to the earth is the same as the force holding the moon, the planets, and other heavenly bodies in their orbits. According to Newton's law of universal gravitation any two masses in the universe attract each other with a gravitational pull. The size of this force is given by:



F is the force between two masses (in Newtons)

m and M are the two masses (in kilograms)

R is the distance between the center of these masses (in metres)

G is the universal constant of gravitation (6.7 x 10-11 Nm2/kg2)



Gravitation is actually a very weak force. The pull is too weak to be felt between two people and it is not even strong enough to pull together two lumps of lead placed right next to each other. It is only when one of the masses is the size of a planet that we can feel the force of gravity.

The huge gravitational force of our nearest star, the Sun, holds together the nine planets of our Solar System. The planets move through space at speeds that just balance the Sun’s gravitational pull, so they are locked into a permanent circle (orbit) around the Sun. Moons orbit planets, and satellites and spacecraft orbit the Earth, in the same way. Satellites are not defying gravity in circling endlessly around the Earth, it is just that they are moving so fast around the Earth that gravity never brings them any closer.



Gravity indicates gravitational force that occurs between the earth and other bodies. Gravity is the force acting to pull objects toward the earth.

Gravity is the force that holds us on the ground and causes objects to fall back to the ground after being thrown in the air.

The force holding objects to the earth's surface depends not only on the Earth's gravitational field but also on other factors, such as the Earth's rotation.

The Earth’s gravitational pull extends out into space in all directions. The further you move away from the center of the Earth the weaker the force becomes.

The measure of the force of gravity on an object is the weight of that object. Weight is measured in newtons (N). The weight of an object changes depending on its location in the universe.

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SUDHANSHU TRIPATHI answered 4 years ago

yes, there is a little difference between the two terms..
Force of Gravity means the force of attraction between any object towards the Earth,
but on the other hand - Gravitational force is the universal force of attraction or repulsion between any two objects in the universe.

Note that Force of gravity will be always attractive force but gravitational force may be attractive or repulsive.
gravitational force when between any body and earth will be known as force of gravity.

Hence force of gravity may be called as gravitational force but gravitational force will be said as force of gravity, when earth is included as a body.

Weightlessness

Weightlessness, or an absence of 'weight', is in fact an absence of stress and strain resulting from externally applied mechanical contact-forces, typically normal forces from floors, seats, beds, scales, and the like. Counterintuitively, a uniform gravitational field does not by itself cause stress or strain, and a body in free fall in such an environment experiences no g-forceacceleration and feels weightless. This is also termed "zero-g" where the term is most correctly understood as meaning "zero g-force."

When bodies are acted upon by non-gravitational forces, as in a centrifuge, a rotating space station, or within a space ship with rockets firing, a sensation of weight is produced, as the contact forces from the moving structure act to overcome the body's inertia. In such cases, a sensation of weight, in the sense of a state of stress can occur, even if the gravitational field was zero. In such cases, g-forces are felt, and bodies are not weightless.

When the gravitational field is non-uniform, a body in free fall suffers tidal effects and is not stress-free. Near a black hole, such tidal effects can be very strong. In the case of the Earth, the effects are minor, especially on objects of relatively small dimension (such as the human body or a spacecraft) and the overall sensation of weightlessness in these cases is preserved. This condition is known as microgravity and it prevails in orbiting spacecraft.