Drill a hole through the moon, drop a cannon ball down the hole. What happens to it?

Question

ie will the ball fall "up into the sky at the other end" or "YoYo" back and forth, eventually resting in the centre of the Moon?

Answer 1

I dont know maybe u can try drilling a hole through the moon?

Answer 2

The ball will yoyo back and forth through the moon's center.

However, a couple of things:

First of all, you can, indeed, neglect the moon's gravity at it's center. There is no gravity from the moon in it's center, because the force of gravity inside a spherical object is ONLY given by the amount of mass BELOW YOU. Put another way, the gravity exerted by a hollow shell on an object inside the shell is zero. Since at the center of the moon, there's nothing below you, (the whole thing's a shell,) there's no gravity (from the moon. The earth still factors in, I suppose, as does the sun, Jupiter, and the rest of the galaxy.)

Secondly, there's a very small amount of atmosphere on the moon, which would contribute a negligible amount of friction. The friction's negligible because of the final point:

Finally, and here's the important part, the ball would keep smacking into the sides of the tunnel. That's because the moon ROTATES, so the velocity of the ball, while starting out lined up with the tunnel, will eventually, as the tunnel rotates around, go out of alignment. It's THAT friction, from the sides of the tunnel, that would slow the ball down until eventually it ended up at the center.

Answer 3

The ball will yo-yo back and forth. The thin atmosphere on the moon (and in the hole) will slowly bring it to a stop at the centre of the Moon.

As the ball falls to the centre of the earth, the gravitational force on it decreases (this still accelerates the ball, but more slowly). At the centre this force vanishes. The ball then passes through the centre of the earth and immediately begins to slow as the force increases again (but pulling in the opposite direction from the motion). The ball pops breifly out of the hole at the other side and then retraces it's steps back to the person who dropped the ball. Any gases (atmosphere in the hole) will cause friction. The ball to return to the sender but not quite as highly as it was dropped from. This repeats, till it stops at the centre.

Interestingly enough: If there is no atmosphere, the moon is a perfect sphere and we assume Newtonian Laws of gravity, then a ball moving in a circular orbit near the surface of the moon takes exactly the same time to return as the one dropped through a hole! The force of gravity inside the hole behaves like an ideal spring (Hookes law). I.e. the force is directly proportional to the distance from the centre of the Moon.

Answer 4

There is no atmosphere on the moon, so provided the cannon ball does not touch the sides of the hole, there are no frictional forces to take energy away from the ball.
The moon's gravity will accelerate the ball, pulling it "down" to the middle, where it arrives with considerable speed. As the ball rushes on its way "up" to the other end of the hole, its speed is this time reduced by the moon's gravity, which, although still acting towards the moon's centre, is now directed against the motion of the ball. It moves slower and slower until all its kinetic energy has been taken away. At this exact moment, the ball will have arrived at the other end of the hole, and the whole process starts again.
It will continue to oscillate like this for ever.
If you could also measure the absolutely tiny oscillations of the moon during the ball's journeys within it, you'd see that the moon would be oscillating back and forth as well. After all, Newton taught us that if a force acts on one body, then an equal but opposite force acts on another body. So as well as the moon pulling on the ball, the ball pulls on the moon with an equal but opposite force.....

Answer 5

When the cannon ball is first released, it has potential energy of, say, x units. This is gradualy converted into kinetic energy as the ball falls, accelerating as it goes. As it reaches the centre of the moon, all of its energy is now kinetic, but the value is slightly (perhaps cvonsiderably) less than x because some energy has been lost due to friction. The frictional losses will only be small but there will be SOME. The ball carries on travelling (upwards now) losing kinetic energy and gaining potential energy until it comes near to the surface again. It will not rise quite so far as the starting point because of the lower energy value it posessed at its new starting point (the centre of the moon). The ball will continue oscillating like this with the oscillations gradually becoming smaller, until it comes to rest at the centre of the moon.

Answer 6

Hi. The Moon's very thin atmosphere would first fall into the hole. The ball would try to push this tiny amount of gas out of the way as it fell, absorbing just a tiny amount of energy. So the ball WILL eventually lose all momentum and come to rest at the Moon's center (which has equal gravity pulling in all directions, so the ball would be in free fall.).

Answer 7

if you drilled a hole through the moon and dropped a cannon bal through it, then theoretically, because the moon orbits the earth due to earths gravity pull i would imagine that the ball would fall towards the earth through the moon and once out of the other side, it would change direction away from the direction it started travelling in and begin to orbit the earth just as the moon does. hope thats any help.

Answer 8

this is an age old question and until we do it we will never realy know but if you assume certain things

like you cant completely negate gravity at the dead centre of the moon and there is no resistance then it will work quite well as a launcher .but in the real world the amount of energy required to remove gravity in the local area to make this work is more then would be required to mass drive it by some other system.

but if we were to do it on our moon the very thin atmosphere would cling down the hole and the gravity would be constant then it will never gain enough momentum to overcome gravity to launch it will keep swinging back and forth until the gas damps out the energy

Answer 9

It will oscilate for a while and because of the friction with the very thin atmosphere it will stop in the midlle. But that would take a very long time because there is almost no gases.
If on the moon there was no atmosphere at all it will go up and down forever.

Answer 10

The cannon ball will, in fact, "yo-yo" to the center of the moon.