Is the science in this comic true?

Question

Please explain to the best of your knowledge.
http://xkcd.com/c162.html

Answer 1

It's very silly, but the basic premise is scientifically sound (though the biological implications are not!)

Theorectically, spinning something bigg enough in the opposite direction will slow the planet, but just because the planet is slowed down doesn't mean she will live any longer! Length of life is based on biological factors, and the units we measure time in are based on physical properties. So if the planet were slowed, our "year" might get longer relatively speaking, but she won't actually live any longer! (In fact, if she continues to use the "day" & "year" based on their definitions, she will theorectically die sooner!)

But it's still funny!

Answer 2

Yeah, it's probably got some truth to it.
For every action, there's an opposite and equal reaction.
And the earth does indeed spin clockwise.

Unfortunately, if we assume the fellow in the cartoon weighs in at 200 pounds and the earth's mass is estimated to be 1.3e25 pounds (that's 13 followed by 26 zeros!) we can easily calculate the effect of his spinning on the earth's rotation. His effect on the earth amounts to 1.5e-25 percent of the earths rotational momentum........
(or 0.0000000000000000000000000015 %!)
At that rate, and assuming his workout is accumulative - i.e. per year additive - if he spins for 66,000,000,000,000,000,000,000,000 years, he will have slowed the earth's spin by 1%. And that's assuming his opposite reaction is directly transmitted to the earth and not converted to heat energy through vibration in the house's structure and surrounding foundation.

Anyway, it was pretty funny.

Answer 3

To the extent that the Earth is a closed system, its angular momentum is a constant. Now the Earth is not really a closed system, but why would spinning in circles make it more or less closed than it already is? I believe the comic is not true.

Answer 4

the motion energy of the whole system earth + little guy is a constant (under the assumption that there is no big 'engine' spinning the earth from the outside).
when he starts moving the little guy takes some of the motion of the earth upon himself. the sum of the motions amounts to the total.
like the answer?

Answer 5

It is true but not to any practical or measureable degree. Also, the momentum the Earth loses it gets back when you stop spinning. Its more a romantic idea than a scientific one.

Answer 6

It may alter it about .00000000000000000000000000000001 seconds for about 100 turns, thats taking a theory to the limit

Answer 7

Only while she's accelerating. And the effect will reverse when she slows down.