Soul Invictus

In light of the recent tragedy that has occured on the Asian continent, the presence of the recent tsunami triggered my remembering something that I had read when I was a child.

I had checked out some sort of cool-facts or "did-you-know"s type of book from the school library. The claim was that if everyone in China had simulataneously jumped up and down at the same time, that the energy would create a tsunami powerful enough to engulf the contiguous United States. As a young child, I found this fascinating. In my adulthood, I'd be curious to know if there is any merit to such a claim, and if this is even plausible at best.

Thanks in advance

Lumen

Let's say that there are N Chinese, with average weight m, jumping from height h. Then the total energy is about
Nmgh
Let's use some conservative numbers here:
Let's say that there are 1.2 billion Chinese
Let's say that they weigh 70 kg each
Let's approximage the acceleration of gravity with 10m/s/s
Let's assume they each jump from a height of 1 m
Then we have
1,200,000,000*70*10*1=840,000,000,000 J
=8.4E11 joules of energy
=0.84 TJ (terajoules)

The earthquake chart at http://www.geop.itu.edu.tr/~onur/seis/energy.html
gives that as equivalent to less than a magnitude 5 earthquake, or about two percent of the energy of the Hiroshima bomb.

Earthquakes of less than magnitude 5 are quite common, and they seldom cause waves of any significant size.

Remember that nuclear bombs release their energy at one location. The jumping of 1.2 billion Chinese would be distributed over a large area, thus diminishing the effect.

I don't think we need to worry about the Chinese initiating a tsunami by jumping simultaneously.

repoman

should be a simple calculation to make.

estimate 1.2 billion people and 50 kg each jumping a generous 30 cm each.

E = 9.8 m/s^2 * 1.2*10^9 *50kg*0.3m = 1.8*10^11 Joules

However one kiloton of TNT releases 4.185*10^12 Joules according to here: http://www.mit.edu:8001/afs/athena/u...5968.As.r.html

So we have about .43 Kilotons - and one Kiloton makes a 4.0 quake. Actually that is still kind of respectable.

damn, I sat on this and Lumen got to it before me. Fairly similar result too...

Soul Invictus

Wow. That's impressive that I got two responses within an hour of my post and of each other. It seems that book was blowing smoke.

I kind of wish I'd learned more about science. You two pulled that calc like it was child's play.

Epictetus

Perhaps the book being cited used very obese Chinese, able to jump 6 feet off the ground?