Gravity and the Universe 8

Gravity and the Universe 8.0

Gravity

The two = forces in nature that are experienced every day are gravity and magnetism. You know that a magnet will attract a refrigerator with a certain amount of force. T= he force depends on the strength of the magnet and the distance between the ma= gnet and the metal. Magnets have two poles -- north and south and either pole wi= ll attract iron or steel. Opposi= tes (north and south) will attract, and like poles will repel. Gravity is the o= ther force we experience everyday. = Newton was the first person to study gravity, and he explained this natural phenom= enon as the law of universal gravitatio= n. Newton = stated that each particle of matter attracts every other particle with a force that is directly proportional to the product of their masses and inversely proporti= onal to the square of the distance between them.

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The standard formula = for gravity

Gravi= tational force =3D (G x m1 x m2) / (d²)

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G is the gravitational constant=

m1 and m2 are the masses of th= e two objects for which you are calculating the force

d is the distance between the center= s of gravity of the two masses.

= Gravity is a force that exists when one ob= ject attracts another. The molecul= es of one object pull on the molecules of another object. An example is the Earth pulling on= you and keeping you on the ground. The molecules of the Earth are pulling on the molecules in you and the molecule= s in you are pulling on the molecules in the Earth. That is an example of how gr= avity at works. Every object in the universe that has mass has a gravitational fo= rce. Even you exert gravity. When you compare mass, you can compare gravitational forces.

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Gravity = is very important on Earth as it pulls everything on or near the Earth toward the center of the Earth. The gravity of other planets also affects Earth. The Moon's gravity makes the tides rise and fall. The Earth's gravity keeps Earth orbiting the Sun, just and t= he Sun's gravity pulls on Earth. As the earth spins, gravity pulls on the clou= ds and the weather can be affected. The gravity of the Earth is 1G. The Earth has this pull on every object. The Earth's gravity a= nd pull that make objects speed up when they are falling. The Earth constantly pulls and objects constantly accelerate.&n= bsp; The atmosphere on Earth creates a lot of resistance and that makes objects move slower. The forces at work are the same. If you dropped a pean= ut in a container with no air (a vac= uum), it would drop just as fast as a bowling ball.

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Conclusion: What is Gravity?

Gravity is a force which tries to pull two objects toward each other.=

Anything that has mass has a gravitational pull.

The more massive an object has, the stronger its gravitational pull i= s.

Earth's gravity keeps you on the ground and causes objects to fall. <= o:p>

Gravity is holds the planets in orbit around the sun.

Gravity keeps the moon in orbit around Earth.

The planets circle the sun and the sun holds them in a gravitational grip.

If the planets didn't have their own momentum, they would fall direct= ly into the sun.

If the planets did slow down, the planets would fall into the sun.

If the planets went faster, they would shoot off themselves into deep space.

The closer you are to an object, the stronger its gravitational pull = is.

Gravity is gives you weight.

Gravity is the force that pulls on all of the mass (matter) in your b= ody.

Go to: http://= www.cs.dartmouth.edu/farid/sciencekids/gravity.html

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Mass and Weight

Remember that mass is a measure of how much material is in an object, and weight is a measure of the gravitational force on that m= aterial in a gravitational field. Mas= s and weight are proportional to each other, with the acceleration due to gravity= as the proportionality constant. Mass is constant for an object and weight dep= ends on the location of the object. If we transported an object of mass m from the Earth to the surface of = the Moon, the gravitational acceleration would change because the radius and ma= ss of the Moon both differ from those of the Earth. Our object has mass m both on the surface of the Earth and on the surface of the Moon, but it will weigh less on the surface of the Moon because the gravitational acceleration there is a factor of 6 less (1/6) than at the surface of the Earth.

Isaac Newton

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Isaac Ne= wton was born a few weeks after his father died.&nb= sp; Newton was born on Christmas Day in 1642 and he died in 1727. The family was very poor. Isaac was a small= and sickly child. He spent a lot of time alone and he enjoyed doing things by himself.= He liked making up games and readi= ng. At the age of ten Newton went to a public school, but he had to room with a druggist whom he did not know. He liked playing tricks on the druggist and = was most likely found himself in more than just a little trouble with the drugg= ist. He made small windmills and kites that flew. He made clocks that could run = on water power. Isaac also drew charcoal sketches and wrote poetry as a young boy. Isaac returned home when he was 14= to help run the farm. His love f= or learning continued and he could often be found studying from his books. Newton was sent to Trinity College in Cambridge. His mathematical skills amazed his professors.

In 1665, England faced a great plague which caused the college to close. Newton had to return home to his mother= 's farm again at the age of 23. = He spent much of his time thinking about gravity and sometimes in the morning hours he would sit on the edge of his bed and think about gravity until din= ner time. He had bought prisms at= a county fair for a few pennies and conducted experiments to show that a beam of sunlight is composed of the six colors of the rainbow. Those colors are red, orange, yellow, green, blue, and violet. Newton ground lenses and mirrors to make a new type of microscope. Newton invented a new type of mathemati= cs called calculus, but grav= ity was something on his mind all the time.

Newton = said that the moon is caught between two forces: the force of gravity, which pul= ls it toward the earth; and centrif= ugal force that is caused by its rotating, which pulls it outward. Since = the moon is held by these two forces it cannot fly toward the earth and it cann= ot fly away from the earth. So, the moon does the next best thing-it moves in a curved path around the earth!

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Sourc= e: The World Book Encyclopedia. World Book-Childcraft International, Inc: Chicago. 1990

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Go to: http://www.sunblock99.org.uk/sb99/people/RWalsh/gravity/grav1.html

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The center of gravity is the exact sp= ot on an object where there is the same amount of weight on one side of the spot = as there is on the opposite side. Once you change the weight anywhere on= the object, the center of gravity changes too. The geographic center of t= he United States (the contiguous states) is l= ocated in north central Kansas. The geodetic center, which allows for the curvature of the earth instead of= the flat plane of a map, is about 50 miles south of the geographic center

Reference: Modified from WonderScience, Han= ds-on Science Activities for Elementary School Teachers and Students, Volume = 10, Number 7, April 1996, American Chemical Society/American Institute of Physics, page 6.

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Gravity = is a very important force.

Every ob= ject in space exerts a gravitational pull on every other.

Gravity = influences the paths taken by everything traveling through space.
Gravity = is the glue that holds together entire galaxies.

Gravity = keeps planets in orbit.

Gravity = It makes it possible to use man-made satellites.

Gravity = makes it possible to go to and return from the Moon.

Gravity = makes planets habitable by trapping gasses and liquids in an atmosphere.

Gravity = can also cause life-destroying asteroids to crash into planets.

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