LITTLE BOY AND FAT MAN...

Eric writes...

Here's one I've always wanted to know: I know how a nuclear bomb works, but in the case of "Little Boy" and "Fat Man" how much matter was needed to be split in order to create the explosions at Hiroshima and Nagasaki. I realize that fission bombs are VERY inefficient, and because of that much more matter was needed, but how much matter had to be separated?

The Hiroshima bomb used about 132 pounds of highly-enriched uranium-235. It exploded with a force equal to 13,000 tons of TNT over Japan's seventh largest city, on 6 August 1945. Some 90% of the city was destroyed.

The explosive charge for the bomb detonated over Nagasaki three days later was provided by about of 18 pounds of plutonium-239. While Little Boy was a uranium gun-type device, Fat Man was a more complicated and powerful plutonium implosion weapon that exploded with a force equal to 20 kilotons of TNT.