Do Klingons use projectiles (with mass, not light)

My physics book contains the following question:

(bolding mine)
So what I want to know is, did the Klingons (or for that matter, anyone) ever fire projectiles? I haven’t watched much Star Trek, but every fight I can remember involved only lasers, which have no mass, and therefore would cause no acceleration on the ship, which is the whole point of the question. Am I correct, or is there some kind of weapon that does have mass?

I do realize, of course, that this whole thread is a bit silly, since the real answer is, “Whatever the Star Trek writers say should happen. The laws of physics don’t always apply in the Star Trek universe, so who’s to say, really?”

Photon torpedoes.

Well, to answer that question, I suppose the effects of inertia on faster-than-light travel would have to be defined. Get back to me when you’ve got a cite for that, m’kay? That’d be great, thanks.

Nowhere in the OP is it mentioned the vehicles are travelling FTL. It’s safe to assume they are on “impulse” and classical physics apply.

Right. But what I don’t know is, whether it is stated within the TV show that they are traveling FTL. A little googling seems to show that they can, but do they during a battle?
Also, I’m nowhere near relativity yet, so I wouldn’t be expected to know at this point that FTL travel is impossible, or even to think about that issue at all.

Aesiron, I assume that “photon torpedoes” have a mass of zero? Are there any other weapons, perhaps mentioned only once, on some obscure episode?

http://ditl.org/datweapon.php?13

“Photon Torpedoes,” despite the name, are not made of photons. They’re actual, physical weapons. They have their name because either:

a) They use small FTL engines for propulsion, or

b) “Photon Torpedo” sounded all kewl and futuristic-ey.

Oh, and the Klingons once supplied a primitive planet with Flintlock muskets during the 23rd century, and were seen using seemingly conventional “mortars” during Deep Space Nine’s later seasons, set in the 2370s.

That link should have been http://ditl.org/menus/lmphotons.gif. Sorry.

God damn it, that link is wrong too.

Just go to ditl.org, click on Weapons, scroll to Photon Torpedoes on the left side of the screen and click on it if you want to read further. I can’t figure out how the hell to get the proper URL to it.