A while back Cecil wrote a column responding to a question about what would happen if everyone in China jumped off their chairs at once. In a related vein comes this story ( http://dailynews.yahoo.com/h/nm/20010907/sc/life_britain_jump_dc_3.html ), culled from today’s headlines. I guess we now have a small scale answer to the question.
Is anyone else wondering what the article meant by “75,000 tons of energy”? If we take the later figure of two billion Joules[sup]*[/sup], then 75,000 seems too low for the number to be referring to kilograms of TNT, and it’s too high to be referring to E=mc[sup]2[/sup]. Anyone know of any other ways to measure energy in tons?
*Given the figure of 20 jumps per minute (suspiciously low) and 110 pounds per kid, this means each jump is about 20 cm, so the figure in Joules is probably reasonable.
It did n’t work. All those kids jumping didn’t make a difference to Mother Earth, so they had no Earth Quake.
It’s about 55,000 US tons, 49,000 Imperial tons, or 50,000 metric tons of children. (One wonders whether that “average 110 pounds” really means “average 50 kg”, which is, of course, not necessarily the same thing.)
Well, they said “weighing 110 pounds each”, not “massing”, so I’ll take that at face value. Besides, at the precision given, and assuming standard Earth-surface gravity, 50 kilograms is 110 pounds.
I’d just like to point out that scales generally work the same way, whether calibrated in metric or english units. And if it is a conversion from metric units, the original almost certainly said “weighing an average of 50 kg.”
But without an explicit tolerance, “about 50 kg” is not the same thing as “about 110 pounds”.
Why does the tolerance need to be explicit? All numbers given in the article are to only two significant figures. In fact, almost all numbers given in any newspaper article are to only two significant figures. I think that we’re justified in assuming that the implicit tolerance here is two significant figures… In which case 50 kg is 110 pounds. Unless you’re arguing that they should only have kept one, and called it 100 pounds?
I’m still wondering about the tons.
You’re assuming two significant figures. But “50 kg” could be only one (given the source).
I realize this is a heck of a bump but XKCD just put out a YouTube video on this question and noted Cecil’s article but claims they do not tell the whole story.
4 minutes long:
