Does it mean going faster than the speed of sound? And what is a sonic boom? And for that matter, what is the speed of sound. Does a bullet from a firearm break the sound barrier?
Yes.
It varies based on the medium and its temperature. Here is a website that will calculate the speed of sound in air based on the temperature (or the temperature required for a specified speed).
Depends on the firearm, but it wouldn’t be unusual.
Sounds like somebody’s looking for help on his homework instead of looking it up himself… :rolleyes:
Simply it means going faster then air (or other states of matter) can get out of the way, This causes the air to build up on the super/hypersonic surface in a high pressure shock wave, which is the sonic boom you hear when it finally gets to you.
Give the kid a beak, he did come to the “Experts” for the information. 
From my limited gun experience, I’d say that handgun and sub-machine gun bullets have speeds near the sound barrier. (some a little above and some a little below). Rifle and machine gun bullets are almost always hypersonic.
Haha, this has made me curious, what happens to a guys hearing when he’s broken the barrier? Does the quality texture or depth of sound change?
I’m gonna venture a guess that the answer depends on whether or not his ears kept up with him. Travel long enough that way, and you can be in tomorrow, while gettin’ hollered at for somethin’ stupid you did yesterday.
You may mean supersonic. I’m not sure there’s widespread agreement, but a common definition of hypersonic is “exceeding five times the speed of sound.” It’s a rare bullet that does this.
Oops! I thought supersonic and hypersonic was the same :o I meant supersonic.