How many Watt does a handgun bullet generate?

Question

We hear about footpounds of force and Joules, but how many Watt (maybe kilowatt?) and how many horsepower does handgun bullets generate, just to try to connect with real world mesurements.

Answer 1

A watt is 1 joule per second.

A 357 magnum bullet weighing 158 grain travels at 1240 ft./sec and therefore generates about 733 Joules.

The next question is how much time elapses when this energy is released.

Using the velocity (1240 ft. per sec.) let's assume that after the bullet strikes a target it loses all of its energy within 1 foot. So traveling at 1240 ft per sec, it will take 1/1240 of a sec for the bullet to go a foot.

733 Joules / (1/1240 sec)

908,920 W

or 908 KW
or 1,219 Horsepower


Or take a 9mm bullet weighing 124 gr traveling at 1150 ft/ sec.; generating 495 J.

495 J / (1/1150 sec.)
569250 Watts

or 569 KW
or 763 Horsepower

Answer 2

Go with Cholsin. A watt is a measure of the rate of energy change, his calculations look right. It may seem strange to produce such vast power, but power is a rate so for the same energy a shorter time gives larger power. If you could stop a bullet instantly you'd get infinite power, but you can't because the bullet deforms.

Answer 3

A 38 Special load, if my math is correct, will generate about 0.075 watt-hour or 0.257 BTU at the muzzle. Kind of puts those movie scenes with the guys being blown back a few yards in perspective, doesn't it?

Answer 4

You are kidding, right? In the real world bullet performance is measured in feet-per-second (FPS) and foot-pounds-of-energy (FPE) not in horsepower, watts or kilowatts.

H

Answer 5

SOME IDIOT SOLD YOU A GUN