my friend said it has something to do with the acceleration of the moon towards the earth? please explain!!!!
2006-10-11 00:54:14 · 9 answers · asked by Ir Jamie 2 in Science & Mathematics ➔ Physics
Imagine throwing a baseball to a friend. As the baseball travels through the air it travels in an arc rather than a straight line due to the pull of gravity. Air resistance causes the ball to slow down as well, so the angle of decent gradually increases too.
The moon is traveling in a similar arc, constantly falling towards earth. However, its distance from the earth doesn't change because the angle of decent given its forward speed is balanced with the gravitational pull and centrifugal forces given the circumference of its orbit from earth. And since the forward motion of the moon remains for all practical purposes, the same, given the relative vacuum of space, it stays in that balance. Our man-made satellites behave the same way.
And now you're wondering, "OK, how did it get there in the first place?"
A popular theory is that a planetary object about the size of mars collided with earth, and the moon is the regrouping of all the debris that the collision left behind. Another theory is that the debris accumulated from some other incoming objects that never did strike the earth. Or lastly, it was formed elsewhere and just so happened to have the correct speed, mass, and angle of approach so as to fall into a stable orbit. We have no definitive proof as of yet, proving the absolute truth in the matter.
A good tool for comparison is the game of tether-ball, where a volleyball is attached to a rope, which is in turn attached to a pole. You hit the ball so that it starts going around the pole, and unless you hit it again and again to keep its speed up, its gradually pulled down towards the pole (earth), and the diameter of its "orbit" decreases.
The time that it takes to travel around the pole remains the same, and if that ball were our moon, it would gradually come closer and closer to the earth. As it got closer, centrifugal forces would increase given the tighter orbit, further slowing the orbital decay. If the forward motion were to continue to decrease however, it would finally reach our atmosphere, causing an abrupt slow down and soon plunge down to the surface. There are some other dynamics at play as well. The gravitational force of the sun and other planets, solar winds, etc.
And while we're on the subject of planets, lets talk about the Earth's magnetic field... it is believed the rotation and tilt of the Earth in relation to the sun may also have been the result of this collision with a Mars sized object.
Also, some believe that the interior of the Earth remains stationary, and only the outer portion rotates - causing the earth to behave like a huge generator, and that in turn is what gives the Earth its magnetic field and North and South pole.
The moon, as you might notice, does not rotate in similar fashion as it orbits the Earth, and even though it does have gravity, it doesn't have a magnetic field - no North and South pole. Some of the other planets don't rotate either. If these theories about rotation are correct, this would seem to demonstrate that gravity and magnetism have separate causes as well.
More could be said about magnetism and electricity, but that would be straying too far from the subject. :-)
2006-10-11 02:42:33 · answer #1 · answered by M Hirsch 2 · 3⤊ 0⤋
I feel is because ther moon is not controled by the gravitational force that pull object down but that does not mean that the moon does not fall it falls around the earthe all the time.
The Moon falls around the Earth all the time. If the Earth did not pull at the Moon, then the Moon would disappear into space, roughly along a straight line. The attraction between the Earth and the Moon pulls the Moon away from that straight line towards the Earth (and likewise pulls the Earth from a straight line towards the Moon), but not enough to make the Moon fall down unto the Earth.
In other words: The Moon has a large sideways speed (not directed towards the Earth, but rather perpendicular to that direction), so when the Moon has fallen a bit towards the Earth, then in the same time it has also moved sideways a bit, so that it is at about the same distance from the Earth as before
2006-10-11 08:06:11 · answer #2 · answered by richy 2 · 1⤊ 1⤋
Ots the same reason that the earth does not fall into the sun. Every object in the Universe is moving in relation to every other. "Orbit" is a precise balance of the gravitatioal attractions of two bodies. Gravity pull the moon towards the Earth, which is moving rocket fast in its owwn orbit around the sun.
Simply put, th Moon IS falling, but is falling AROUND the earth, not into it.
2006-10-11 08:07:27 · answer #3 · answered by chocolahoma 7 · 1⤊ 0⤋
Tie a ball with a string about 2 feet long. Hold the ball above the hand that is holding the string. Let the ball go. Now take and spin the ball with the string and let it go. By spinning around the earth the force keeps it from falling into the earth. Just like the earth spinning around the sun
2006-10-11 08:05:58 · answer #4 · answered by Captleemo 3 · 0⤊ 0⤋
The Moon's orbit is what keeps it from hitting the earth.
The circular path is a product of two things:
1) the earth pulling the moon towards it
2)The moon moving perpendicularly to the earth.
Together these form a circular path, and as there is no resistance to the moons motion, it shall continue happily with the angular velocity it currently carries.
However, the Moon is very slowly moving towards the Earth, but not at any speed you need to worry about.
2006-10-11 07:58:44 · answer #5 · answered by Stuart T 3 · 1⤊ 2⤋
Becz moon is in a state of equilibrium in which the moon wants to fly away but earth's gravitational force is pulling it back as a result moon always rotate around earth
2006-10-11 08:36:54 · answer #6 · answered by Manpreet 1 · 0⤊ 1⤋
because the moon was once part of the earth and was shot away from it. The moon is orbiting the earth and thus is pulling away from the earth. The earth's gravity is pulling it back!
2006-10-11 07:57:46 · answer #7 · answered by Rvardell 3 · 1⤊ 1⤋
The moon's rotation involves centripetal force=mv^2/r ; where the value of v doesn't exceed 11.2 km/s (escape velocity) only when the velocity of an objecr ios le3ss than 11.2km/s it comes back to earth
2006-10-11 08:05:50 · answer #8 · answered by Anonymous · 0⤊ 1⤋
Cause God wants it there
2006-10-11 07:56:16 · answer #9 · answered by da dude 4 · 0⤊ 5⤋