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Can it be found on the periodic table?
It’s a good idea. Sort of like Jonathan Swift’s proposal to end poverty in Ireland was a good idea.
????? = begat
??? = unleavened bread
???? = levirate marriage
Aha, I think I see where we differ in this ridiculous hypothetical discussion. You see, I was assuming that if gravity was turned off, the planet disintegrated. It’s pretty much impossible to predict how the laws of physics will behave if you’re starting from the premise that certain important laws will be ignored.
feivel – My rebuttal shall be limited to the sentence you replaced with a “…” from that article:
“Things not attached to the Earth in any other way would fly off into space in a straight line that would take them away from the surface of the Earth.”
Thanks for the discussion.
feivel – a person would move according to his tangential velocity, not his angular velocity. Angular velocity is only pertinent to circular motion, and he would no longer be spinning – that’s the point. A person’s tangential velocity at the surface of the earth is almost 30 km/sec! I’d call that flying, not “slowly rising”…
But you’re right that gravity isn’t required for friction. Normal force is required for friction. While it’s true that normal force often comes from gravity, it doesn’t have to! It’s another one of these forces that doesn’t really exist in it’s own right…
Centripetal force is not a force that exists in its own right. In order for an object to remain in circular motion, there needs to be a force ALREADY pulling the object towards the centre of the circle to PROVIDE centripetal force.
For example, in swinging a yoyo in a circle, the force of tension provides centripetal force. When a car drives around a sharp curve, the force of friction provides centripetal force. And when a person stands on the Earth, the force of gravity provides centripetal force.
Therefore, if Earth’s gravity turned off, a person would simply continue to follow his tangential velocity and fly off into space. (Of course, the whole planet would have disintegrated as well, so you might not notice.)
Centripetal force doesn’t have much to do with the dizziness. While it’s true that the earth is moving more rapidly than the merry-go-round, in fact, one’s ANGULAR velocity is much, much less than on a merry-go-round. This is why you wouldn’t get dizzy.
Centrifugal force is fictitious. What you are talking about is centripetal force. And by the nature of circular motion, you’re ALWAYS accelerating.
Do you feel like you’re traveling 250 km/h on an airplane? Unless you’re accelerating significabtly, you can’t really feel it unless you can clearly see that you’re moving at a different speed than your surroundings. (Look up inertial reference frames.)
Quantum theory basically says that energy can only exist in discrete quanta (basically specific amounts that increase in jumps). This is related to the shells – for an electron to become “excited” (or jump) to a different shell, it has to gain that specific amount of energy.
I’m not sure which experiment you are referring to, but if you mean the one involving hydrogen spectra, it’s basically like this:
He filled a tube with hydrogen gas and shot some electricity at it. The tube then emitted light. However, instead of seeing a nice contiguous rainbow of colours, he saw discrete, disconnected bars of colour. The reason for this is because the electrons in the hydrogen gas were absorbing these specific quanta of energy they needed to become excited to a higher shell. However, electrons don’t particularly like to be excited – they like to be in the “ground state”, or shell number one. Therefore, they immediately hop back down to the ground state and EMIT this energy they absorbed as LIGHT.
Now to the quantum theory: Since the electrons could only absorb specific quanta of energy to become excited, they can only emit the same quanta of energy when they hop back down! This is why only certain colours were emitted from the tube. Each colour corresponded to a different energy lever which corresponded to a different shell of the hydrogen atom.