Veda #66 : Silencer

Day 66
"Why does gun silencer could supress the sound of the gun?"


Too much police drama, and too much watching suspense film. Usually the bad guy or the assassins using the silencer for the gun, to kill their victim silently. how does the barrel in front of the gun could reduce the sound of the projectile?

Imagine a balloon. If you pop a balloon with a pin, it will make a loud noise. But if you were to untie the end of the balloon and let the air out slowly, you could pop it making very little noise. That is the basic idea behind a gun silencer.
To fire a bullet from a gun, gunpowder is ignited behind the bullet. The gunpowder creates a high-pressure pulse of hot gas. The pressure of the gas forces the bullet down the barrel of the gun. When the bullet exits the end of the barrel, it is like uncorking a bottle. With the pressure abround 3000 psi, it could produce loud POP.

Now let's add the silencer. A silencer screws on to the end of the barrel and has a huge volume compared to the barrel (thats why you usually see the silencer is always bigger than the gun's barrel). With the silencer in place, the pressurized gas behind the bullet has a big space to expand into. So the pressure of the hot gas reduced greatly. When the bullet finally exits through the hole in the silencer, the pressure being uncorked is much lower, around 60 psi. Therefore, the sound of the gun firing is much softer.