# Weightlessness in Physics | Definition, Examples – Gravitation

Weightlessness Definition Physics:
It is a situation in which the effective weight of the body becomes zero.

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## Weightlessness in Physics | Definition, Examples – Gravitation

Weightlessness is achieved
(i) During freely falling body under gravity.
(ii) Inside a space craft or satellite.
(iii) At the centre of the earth.
(iv) When a body is lying in a freely falling lift.

Weightlessness Meaning:
Weightless sensations exist when all contact forces are removed. When in free fall, the only force acting upon your body is the force of gravity a non-contact force.

Weightlessness is the complete or near-complete absence of the sensation of weight. This is also termed zero-G, although the more correct term is “zero G-force”. It occurs in the absence of any contact forces upon objects including the human body.

### Weightlessness Examples

Weightlessness is the feeling experienced when no counter force is acting on the body.

• A man who is Paragliding
• Astronauts on the moon
• When a lift suddenly snaps and you are lifted off your feet.

Taking the example of the roller-coaster which is constrained to follow a track, then the condition for weightlessness is met when the downward acceleration of your seat is equal to the acceleration of gravity.

Considering the path of the roller-coaster to be a segment of a circle so that it can be related to the centripetal acceleration, the condition for weightlessness is

Vweightlessness = $$\sqrt{g r}$$

From the Centripetal acceleration realtionship v² = g

Gravitation:
Have you ever thought, when we throw a ball above the ground level, why it returns back to the ground. It’s because of gravity. When a ball is thrown above the ground in the opposite direction, a gravitational force acts on it which pulls it downwards and makes it fall. This phenomena is called gravitation.

Learn relation between gravitational field and potential field, Kepler’s law of planetary, weightlessness of objects in absence of gravitation, etc.