What if every chinese person jumped off a chair at once… and yelled?

Okay, here’s the nutshell version. I started a post to this, with ALL the physics worked out, and it friggin’ erased itself 'cuz my cookie expired. :smack:

**Part 1: What if they jumped?**

Newton’s third law applies here: as Cecil said, for every action there is an equal and opposite reaction. (Pushing down on the earth to jump off a chair) + (the work required to get UP that chair) - (the force of the impact when landing) = about net Zero. BUT, just for laughs, I did the math…

And the ratio of the weight of every single chinese person to the weight of the earth is about 0.00000000125 (something around 1.4 E^-9). To give you an idea of how insignificant this is, Mount Everest (a MUCH more interesting and powerful rotational-anomaly) is several hundred thousand times more massive, and has several thousand times the impact per-person of the pitiful chinese jumping masses. I’ve done the math, it’s tiny.

**Part 2: What if they all yelled? Would we hear it?**

Well, THAT gets more interesting. Cecil didn’t wanna go into this, but I figure what the heck. So here’s the basic thing: sound is additive logarithmically. If two sounds are played synchronously at the same location, the resultant sound is equal to the individual sound + 3dB. Ex, two 70 db sounds result in one 73 dB sound. Now, lets assume we have 1.27 BILLION chinese, and somehow we’ve managed to pack them into an undampened, centralized, tight-as-can-be area with no outside dampening. If they all screamed at once, the additive sound would be close to that of a nuclear blast, around 220 db (the basic gist of THAT being that the sequence for more than one sound would be x^0.05). Here’s how you figure that: 1 person + 1 person = 2 people at x+3. 2 people + 2 people = 4 people at x+6. 4+4=8 at x+9, and so on. The result is a **logarithmic function**. So your original sound of 128 db for a human scream, plugged into that formula, gives us:

Loudness = 128 + 4.3281 * (ln (x)), where x is the number of people screaming.

For 1.27 billion people, the result is about 218 db, close to that of a nuclear blast. Now, keep in mind, human death occurs at sounds upwards of 200-205 db. A nuclear blast isn’t even sound anymore, just a blast wave - carries enough energy to rip apart the human body.

Tasty, eh?

Now, the harest part of all. Would the sound reach us here in the US? Well, the dissipation of sound over distance in air is -6 db for every doubling in distance starting at 1 foot. The formula for this is

Loudness = 218 db - 8.65617 * (ln (x))

We can hear sounds as low as 10 db (whisper). So if we solve for 10 db as loudness, we get

24.029 = ln x

e^24.029 = e^(ln x), x = e^24.029

X distance = 2.72714 * 10^10 feet, or 5.165 million miles.

I gawked at that figure myself, but then I realized that this can easily be changed by dampening forces well outside the realm of human computation.

The real question here is whether or not we would actually hear it due to the curvature of the earth. Because the dissipaiton of sound would be greater due to the earth’s curvature, and the fact that physical blockades (japanese mountains, ocean fronts, and the Rockies) would get in the way, we MIGHT hear it… but probably not. Think: did we hear the sound from the blasts at Hiroshima and Nagasaki? I haven’t found any evidence to support it.

So, what’s the upshot? Here’s the answer:

- We would probably not hear it here in the USA.
- Even if we did, it would take the sound about 5.7 hours to reach Los Angeles, about 9 hours to reach New York.
- EVEN IF you could get all the Chinese to yell at the same time, the resulting sonic blast would kill everyone in the vicinity of the sound.

Peace!