why there is no gravity in space? and why there is gravity in earth?

Answer 1

Gravity is a force of attraction generated by objects with mass. Even your body exerts gravity. At a distance from a large object like a planet (which has a strong gravity field) the effects of gravity are less noticeable.

Answer 2

There is gravity in both! The earth has gravity all the way to the core. The Sun provides most of the gravity in space but the other objects in space have gravity too. It simply depends on your proximity to the object in question. You and I even have gravity. Since we are relatively small objects are gravity is very faint. In space it seems like there is no gravity because we may be so far from a source of major gravity that we cannot feel it. As far as someone floating into outer space: that certainly can happen, but think of it like this- a person's body would be similar to a millionth of the size of a small dust particle that you may see in your house when a sun ray hits it. You know the kind that just floats in the air for who knows how long.

Answer 3

Where there is matter, there is gravity. It's just a function of matter. Other forces keep the particles in an atom from flying apart, or create a relationship between electricity and magnetism.

The reason satelites and spacecraft don't fall down is that they are in orbit. They are moving around the Earth at a speed that exactly matches the force of gravity at that altitude. More speed, more altitude. Less speed, less altitude. If you go fast enough, you can overcome the force of gravity and reach "escape velocity". If you go slow enough, your orbit is so low that air friction makes your orbit unstable and you fall back to Earth. When a spacecraft returns to Earth, it doesn't aim AT the Earth. It fires rockets in the direction of its travel to slow down and drop out of orbit.

You can think of Earth's gravity as a sloping cone around the Earth. Out by the Moon, the slope is so gradual that it can take 29 1/2 days to go around Earth without falling in. Closer in, where all the "geosynchronous" TV,communications and weather satellites are, the slope is a little steeper and a 24-hour trip is required. A hundred miles from the surface, the slope is steep enough that you need to circle the Earth every hour to keep from falling down the slope. The gravity is there, but it is limited by distance.

You have gravity too. If there weren't bigger bodies interfering with the effect, and if you had a LOT of patience (and oxygen), you could demonstrate it. The best example so far is an asteroid that astronomers recently observed that appears to be a collection of smaller asteroids that drifted together and are held by their combined, weak gravity.

Answer 4

There is gravity in space. There's just no surface for the gravity to push you up against.

Gravity tries to make objects "freefall". If you are in freefall, then you are in zero g, and don't feel a force from gravity. The gravity of the Earth pulls us down to the surface. It's the upwards force of the surface, preventing you from freefalling, that you feel as the gravitational force. Suppose you dug a big tunnel through the Earth. If you jumped in, as you fell you would feel no gravity. Similarly, if you built a very big tower that was tall enough to reach into space, you would still feel gravity standing on the platform on the top.

As Newton pointed out, it is the Earth's gravity that makes the Moon orbit around it.

Answer 5

You always have gravity. The problem is that sometimes it is almost insignificant! But it is produced by the effect of mass. The bigger the mass (object) more gravity will be created. In space you can find massive (huge) amounts of gravity in black holes. They are stars that collapse under their own weight.

On earth, we have gravity because our planet has a big mass compared with our mass. Therefore, we "feel" the earth pulling us down to the ground.

Answer 6

Actually, there is gravity everywhere in the universe. There is just less of it in space because you would be far enough from the Earth to not feel the effects as much. Go to the vicinity of Jupiter and the gravity would be ten times as great as it is higher. There is still gravity on the space station - its just called "micro-gravity".

Answer 7

Gravity is created by the rotation of a spinning spacial body(Earth or any other planetary body that rotates) the rate of spin and size of the planet determines the gravity strength. That is why the Earth has a stronger gravity than say Luna(the moon).We are much larger thus the stronger gravitational pull.Space itself is the vacuum between these gravity fields.If the Earth were to suddenly stop spinning our atmosphere and eventually us would drift off the surface as gravity failed.

Answer 8

Gravity is relative. It is generated by objects with large mass. Planets have a lot of mass. Space has very little mass, so the gravity in space is very weak. But the closer in space you get to an object with a large mass, the stronger the gravity is toward it.

Answer 9

There is lots of gravity in space.

In fact, astronauts in low Earth orbits (like in the Shuttle), are subject to almost as much gravity from Earth as we are on the surface.

F = G * M1 * M2 / d^2

M1 is the mass of Earth, M2 the mass of the astronaut, G the gravitation constant and d the distance between the anstronaut and the centre of Earth.

On the surface or in orbit, G, M1 and M2 are the same. Only d changes.

On the surface, d = 6250 km,
In a low orbit (h= 150 km, for example), d=6400

The ratio of the squares is 0.95
The astronaut is still subject to 95% of the gravity that affects us on the surface.

The difference is that we have the surface pushing up on us, to keep us from falling to the centre. That is "weight".
The astronaut is in free fall (nothing stopping his fall). It is his sideways speed that keeps in from hitting Earth: he is in orbit. Stop the sideways movement and he falls straight down (until something pushes back up at him, like the ground... suddenly)

PS:
The spin has very little to do with gravity. In fact, the very little effect it has is to reduce the impression of gravity by providing a centrifugal effect (pushing things away from the centre).

We do not know what "causes" gravity. Einstein's theory proposes that concentration of mass causes a deformation of the geometry of space such that the closer you are to a large mass, the lower your gravitational potential energy. The natural tendency for objects is to seek the lowest state of potential energy.

Nevertheless, since Newton, we know that the more mass an object has AND the closer we are to it, the more force we feel.

Answer 10

Gravity is the result of the centrifugal force created by the rotation of the earth on it's axis. Just as you can spin a container of liquid fast enough to keep the liquid inside the container, so too does that same principle keep all of us from flying off the planet.
In space, large bodies (moons, planets, even some of the larger meteors and asteroids) have some limited gravitation pull, even if they don't have an axis on which to spin, simply because of their sheer mass. Space does spin on an axis creating centrifugal force, and it has no mass, so it has no gravity.