Physics for Future Presidents

TNT then detonates as a chemical chain reaction. In a millionth of a second, the energy of the springs is transformed into energy of motion. The molecules have high velocity, and that means they are hot.

It can do this because (unlike gasoline or chocolate chip cookies) it doesn’t have to be combined with air.

TNT is used not because of its high energy content, but because it can release its energy very rapidly.

chocolate chip cookies deliver about 5 food calories of energy per gram (the weight of about 2 chocolate chips), a number you can find in any diet book, whereas TNT delivers only 0.65 food calories per gram—nine times less.

Gasoline has more energy than TNT? Yes, much more. In fact, even chocolate chip cookies have more energy than TNT.

“Will it work?” The answer is, invariably, “I can’t say that it wouldn’t.”

That fact surprises most people, but it makes sense if you think about it. TNT is used not because of its high energy content, but because it can release its energy very rapidly. It can do this because (unlike gasoline or chocolate chip cookies) it doesn’t have to be combined with air. The atoms in the TNT molecules are analogous to compressed springs held by a catch; release the catch, and the energy comes flying out. Break one molecule of TNT, and the energy breaks the adjacent catches. TNT then detonates as a chemical chain reaction. In a millionth of a second, the energy of the springs is transformed into energy of motion. The molecules have high velocity, and that means they are hot.

Gasoline has more energy than TNT? Yes, much more. In fact, even chocolate chip cookies have more energy than TNT. If you want to destroy a car, you can use a stick of TNT. But an equal weight of chocolate chip cookies, fed (for example) to teenagers with sledgehammers, can accomplish far more destruction. The chocolate chip cookies deliver about 5 food calories of energy per gram (the weight of about 2 chocolate chips), a number you can find in any diet book, whereas TNT delivers only 0.65 food calories per gram—nine times less.