why earth should have gravitational force?why not repulsion force?

Answer 1

Maybe when we have a completed GUT theory (grand unification theory) of everything, we will be able to describe why gravity is always attractive.

Aloha

Answer 2

Because if it had a repulsive force, there would be no Earth. The attractive force of gravity holds our planet together.

Answer 3

How might want to an analogous stress be pushing upward and downward together? Gravity is an charm between 2 gadgets with mass. because the Earth has this kind of massive mass, it pulls people in route of it. It you've been on a planet like Jupiter (if it replaced into sturdy), you may want to be beaten because the gravity is so great there. the floor does exert a classic stress to stay away from people and different gadgets from falling. gadgets floating in water is by using a stress referred to as buoyancy.

Answer 4

In physics, gravitation or gravity is the tendency of objects with mass to accelerate toward each other. Gravitation is one of the four fundamental interactions in nature, the other three being the electromagnetic force, the weak nuclear force, and the strong nuclear force. Gravitation is the weakest of these interactions, but acts over great distances and is always attractive. In classical mechanics, gravitation arises out of the force of gravity (which is often used as a synonym for gravitation). In general relativity, gravitation arises out of spacetime being curved by the presence of mass, and is not a force. In quantum gravity theories, either the graviton is the postulated carrier of the gravitational force[1], or time-space itself is envisioned as discrete in nature, or both.

The gravitational attraction of the earth endows objects with weight and causes them to fall to the ground when dropped (the earth also moves toward the object, but only by an infinitesimal amount). Moreover, gravitation is the reason for the very existence of the earth, the sun, and other celestial bodies; without it matter would not have coalesced into these bodies and life as we know it would not exist. Gravitation is also responsible for keeping the earth and the other planets in their orbits around the sun, the moon in its orbit around the earth, for the formation of tides, and for various other natural phenomena that we observe.

A vast number of mechanical contrivances depend in some way on gravity for their operation. For example, a height difference can provide a useful pressure in a liquid, as in the case of an intravenous drip or a water tower. The gravitational potential energy of water supplies hydroelectricity can also be used to power a tramcar up an incline, using a system of water tanks and pulleys. Also, a weight hanging from a cable over a pulley provides a constant tension in the cable, including the part on the other side of the pulley to the weight.

Examples are numerous: For example molten lead, when poured into the top of a shot tower, will coalesce into a rain of spherical lead shot, first separating into droplets, forming molten spheres, and finally freezing solid, undergoing many of the same effects as meteoritic tektites, which will cool into spherical, or near-spherical shapes in free-fall. Also, a fractionation tower can be used to manufacture some materials by separating out the material components based on their specific gravity. Weight-driven clocks are powered by gravitational potential energy, and pendulum clocks depend on gravity to regulate time. Artificial satellites are an application of gravitation which was mathematically described in Newton's Principia.

Gravity is used in geophysical exploration to investigate density contrasts in the subsurface of the Earth. Sensitive gravimeters use a complicated spring and mass system (in most cases) to measure the strength of the "downward" component of the gravitational force at a point. Measuring many stations over an area reveals anomalies measured in mGal or microGal (1 gal is 1 cm/s^2. Average gravitational acceleration is about 981 gal, or 981,000 mGal.). After corrections for the obliqueness of the Earth, elevation, terrain, instrument drift, etc., these anomalies reveal areas of higher or lower density in the crust. This method is used extensively in mineral and petroleum exploration, as well as time-lapse groundwater modeling. The newest instruments are sensitive enough to read the gravitational pull of the operator standing over them.

Answer 5

No one really wants to address the real answer. There is no such thing as Gravity. In truth, the Earth simply SUCKS! That is what keeps us on the surface.

Answer 6

No one knows for sure. Perhaps the laws of physics are different in different universes (if they exist). Perhaps these laws will change after our universe collapses and forms another big bang.

All science can do is describe and measure the effects it observes.

Answer 7

Your penalty for asking this question is that you have to get a degree in Physics.

Answer 8

cause it keeps on the ground
cause it keeps us in the suns orbit
cause it keeps us alive
cause it keeps to the natural balance of the universe
cause it works

cause why not?

Answer 9

One word, Mass.