Newton’s Law of Universal Gravitation states that every object in the universe attracts every other object with a force that is directly proportional to the mass of the objects and inversely proportional to the square of the distance between them. This law was first proposed by Sir Isaac Newton in 1687 and has since been proven correct through extensive experimental evidence.
Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun. Earth’s gravity is what keeps you on the ground and what makes things fall.
The strength of gravity between two masses is given by:
F = G * (m1 * m2) / d2
where F is the force of gravity in Newtons, m1 and m2 are the masses of the two objects in kilograms, d is the distance between the two objects in meters, and G is the gravitational constant.
The value of the gravitational constant is:
G = 6.67 x 10-11 N * m2 / kg2
Sir Isaac Newton was an English physicist and mathematician who lived from 1642 to 1727. He is considered one of the most important scientists in history for his work on mechanics, optics, and calculus. Newton’s Law of Universal Gravitation was just one of his many contributions to science.
Gravity is a little hard to define since it combines four forces—gravity, magnetism, electricity and nuclear fusion—which are all said to be mysterious. Gravity is one of the four fundamental forces in the universe, according to popular belief. According to Sir Isaac Newton’s research in 1687, gravity is an effect caused by attraction between two bodies (Eddington 93).
Without gravity, everything would stay put unless something acted on it; therefore, it would move indefinitely because there would be no force to stop it. Perhaps the best place to start when trying to understand this topic would be with a simple item such as an apple (after all, it was what “sparked” Newton’s creativity).
An apple falls from a tree at a velocity of 9.8 m/s^2 (32.2 ft/s^2) due to the pull of gravity. The force of gravity is equal to the mass of the object times the acceleration of gravity. F=mg, where m is the mass in kg and g is the acceleration of gravity, which is 9.8 N/kg (about 32 ft/lbsec^2). This value is constant at the Earth’s surface regardless of an object’s mass. So, a 1 kg apple falling at 9.8m/s^2 will have the same weight as a 10 kg boulder falling at 9.8m/s^2; they will both have a weight of about 98 Newtons.
An object’s weight is the force of gravity on that object. The value of gravity (acceleration) is different on other planets and even satellites; for example, the acceleration of gravity is only 3.7 m/s^2 (about 12 ft/sec^2) on Mars. This means that an object that has a mass of 1 kg on Earth would only have a weight of 3.7 N on Mars (about one-third its weight on Earth).
Gravity also affects fluids; in particular, it affects how fluids flow. Fluids are composed of molecules that are in constant motion. The motion of the fluid molecules is affected by gravity and the molecules’ interactions with each other. Gravity affects the motion of fluid molecules in two ways: it pulls them down, and it slows them down.
Gravity pulls fluid molecules down because they have mass. The force of gravity on a fluid molecule is proportional to its mass. So, the more massive a fluid molecule is, the more gravity pulls on it.
Gravity also slows fluid molecules down. When a fluid molecule moves, it collides with other molecules in the fluid. These collisions transfer energy from the moving molecule to the other molecules in the fluid. Gravity slows down moving molecules because it makes them collide more often with other molecules.
The combined effect of these two forces (the force of gravity and the force of collisions) is to make fluid molecules move slower at the bottom of a container than they do at the top. This difference in speed is called a velocity gradient, and it is caused by gravity.
The velocity gradient is important because it determines how fluids flow. The steeper the velocity gradient, the faster the fluid flows. Gravity makes the velocity gradient steeper near the surface of a planet, so fluids tend to flow faster near the surface than they do deep underground.
Gravity also affects the motion of objects in space. Objects in space are not affected by air resistance, so they can move much faster than objects on Earth. Gravity still affects their motion, however. Gravity pulls objects toward the center of a planet or satellite. The closer an object is to the center of a planet, the stronger the force of gravity on it.
The force of gravity also affects the orbit of a satellite. A satellite is any object that orbits another object in space. The most familiar type of satellite is a moon, which orbits a planet. Gravity pulls satellites toward the center of their orbit. The closer a satellite is to the center of its orbit, the stronger the force of gravity on it.
The apple was one of the two curiosities (the other being the moon) that prompted Isaac Newton to develop The Law of Universal Gravitation in 1666 (Eddington 93). It is the tale of an apple falling to the ground, according as Newton later wrote, that caused him to ask if this same force was also keeping the moon in position (Gamow 41). As Galileo had observed, objects descended at a rate of about 9. 8 meters per second seconds.
He also knew that the moon’s orbit was much larger and took about 27. 3 days to complete one revolution. From this, he reasoned that there must be a force that decreases with distance between two masses (Eddington 93).
The Third Law of Motion states that every force exerted by one object on another is equal to a force, but in the opposite direction (every reaction has an equal but opposite eaction). So the pull of the earth on the apple is comparable to the push of the apple back on the earth.
But he didn’t know why. It wasn’t until Newton that we understood the reason for elliptical orbits, and it has to do with his famous Law of Gravity.
Gravity is the force by which a planet or other body draws objects toward its center. The force of gravity keeps all of the planets in orbit around the sun. Earth’s gravity is what keeps you on the ground and what makes things fall.
Anything that has mass also has gravity. Objects with more mass have more gravity. Gravity also gets weaker with distance. So, the closer objects are to each other, the stronger their gravitational pull is.
Earth’s gravity comes from all its mass. All its mass makes a combined gravitational pull on all the mass in your body. That’s what gives you weight. And if you were on a planet with less mass than Earth, you would weigh less than you do here.