Explain gravity?

Question

OK, I thought I was smart until my son asked me this question. I can't for the life of me remember what it is. My son asked me, "why don't we fly off the earth." All I can remember is that "the earth sucks!" Well, that gave me a few brownie points and a laugh but still I can't remember the answer. So, why does gravity pull us down and we don't fly off the earth, since the earth is a spinning ball?

Thanks

Answer 1

There's always gravitational force between two masses - that means there is gravitational force between you and the earth. Since the earth is SO massive, it's gravitational force causes you to stay on its surface.

For more on gravity, check out Wikipedia:
http://en.wikipedia.org/wiki/Gravity

Answer 2

Gravity is a result of a basic property of all objects in the universe. The more massive the object, the greater its gravity. An object's gravitational field attracts another object with a force that is related to the distance between the centers of the two objects and their masses. The smaller the distance between the centers of the objects, and/or the greater their masses - the greater the attraction. Mathematically, this relationship is written:




F is the gravitational force between the two objects, m1 and m2 are the masses of the two objects, and r2 is the square of the distance between the centers of the two objects. The symbol, (the Greek letter "a") means "is proportional to." As two objects get further apart, their mutual attraction decreases pretty fast. The relationship above is also known as "Newton's Law of Universal Gravitation."

You can see that, mathematically, the gravitational force between two objects can get very small, but it can never be quite zero. So how small a gravitational force do you need to carry out "microgravity" experiments?

To scientists, a "Microgravity Environment" is one in which the apparent weight of a system is small compared to its actual weight due to gravity on Earth. "Small" is a relative term, however, a common example is an apparent weight of one millionth that on Earth's surface.

That's 0.000001 times less than on Earth - nearly, but not quite, weightless. Using the gravity relationship above, you can calculate how far away you need to be from Earth to achieve near-weightlessness. Remember that force is proportional to 1/r2, and that the distance (r) is measured as the distance between the centers of the objects. Therefore, for a laboratory on the surface of Earth, r becomes Earth's radius (6,370 kilometers) The math:

re: Radius of Earth
Fe: Force at surface of Earth
Fµ: Force in microgravity environment (10-6*Fe)
rµ: distance to microgravity environment




In other words, to achieve one millionth the force of gravity on the surface of Earth, you have to move your laboratory a distance equal to the square root of one million (one thousand) units further away from the center of Earth . That's 1000 Earth radii (or 6,370,000 kilometers)! The moon is only about 60 Earth radii away (384,401 kilometers)!!

Answer 3

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.

Answer 4

Gravity is strange and complicated, but you can think of it in terms of a ball on a sheet pulled tight. When you put the ball on the sheet, the sheet bends inward, and other things roll toward it. This is a perfect analogy for gravity, because all things with mass have gravity--the more mass, the more gravity, the more the sheet "sinks," and the more things get pulled toward it. In fact, gravity is theorized to be an actual warping of spacetime in the way that the sheet is warped by the heavy ball.

Answer 5

How does the Bible clarify electric powered screwdrivers? they don't look to be appropriate with the exception that gravity explains really how evolution befell in the international. without gravity, planets doesn't carry at the same time and existence doesn't have happen. Einstein defined gravity as a bending of area as a results of mass. Gravity is physics and evolution is its personal technological information. they don't look to be depending on one yet another as sciences.

Answer 6

Gravity as observed, is possibly already explained by others so far.

Our current knowledge of physics is almost as bad as medicine. Our so called scientists settle for symptoms and the best they manage is to approximate formulas within boundaries they can a grant for.

Convenient cliches are regurgitated as "centrifugal forces" holding us on earth.

A recent observation of galaxies moving apart after a local big bang, has indicated that the rate of expansion is much faster than can be accounted for by calculating the amount of visible matter - causing gravity !

In other words, our shy scientists have just discovered that there are forces termed as dark matter and dark energy accounting for 97% of what is around us - yet totally invisible to current science !?

Very little research in dark matter is pursued.

Some anti-gravity is probably responsible for holding planets like our solar system in stable orbits. Gravity as formulated by "science" would have collpsed every object long time ago!

Answer 7

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.

Answer 8

In this universe all the matter attract each other. It is a basic quality of matter. The attraction is proportional to the mass of the matter and the distance between them. Higher attraction when it is closer and no attraction far away like infinity So the earth being very big it has a greater pull than your pull. SO the earth wins and pull you down

Answer 9

Whew,
You want a quick explaination don't you?
Ok, I'll try.
10 There are more forces than those that are commonly referred to.

Gravity is a by-product of a couple of those.
thats the technical explaination...
Another way to think of it is... picture grains of sand on a beach.
you get them wet, pack them in a ball (compacting them) they become more dense.. (The ball of sand does.)
kindof the same general idea.
the more compact elements get, the more gravity they produce.
The heavier an element is, the more gravity.
The earth has an Iron core.
Picture a red hot ball of molten... crystalline iron.. the size of... say.... Mercury.
It's this core that "depresses" the "Fabric" of space far enough to create the 1-g of gravity we have.

Picture a bed sheet tied to the four corners of a room tightly.
toss a marble in the center.
Now toss another one. (It would eventually roll it's way to the center with the other one)
Now toss another.. another.. another.
Now looking at it, it would resemble a kind of funnel shape in the middle.
This is what gravity looks like to mathamaticians.

Beyond this kind of confusing answer. You really have to know some math... Trig... calculus.. etc.
Does this help at all?

Answer 10

Basically, it is an energy source. The equation for this force is c2 = E/m. As either the mass or energy within a solar mass changes so, also, does the gravitational field.

At http://360.yahoo.com/noddarc you will find a writing, "Time, Energy, and Gravity". It is 4-5 pages long and easy to understand.