Latisha asked:
I need to know for this science project I have. I need to figure out the physics of archery. How fast (km/hour) do lightweight, ~2 gram arrows go at?
haha, I just realized how light 2 gram arrows are. I found this one arrow, though, that was used by people who can’t afford real ones and made it, and it was super light and made out of a stick and other such things, so that’s why. just in case this seemed too ridiculous.
That would depend on a lot of other things, what type of bow, how heavy the bow, draw length, etc. But the fastest setup around, a compound bow, with the lightest arrow made for the bow, can launch arrows up to 300 fps, that’s 329 km/hour.
Now 2 gram, is a bit light for arrows, way light. 2 grams would be about 30 grains, that’s the weight of just the arrow point. My arrows have 110 grain points, so the points alone are about 6 almost 7 grams. My complete arrow is about 340 grains, so 22 grams, 43 lbs recurve bow 31″ draw arrows are flying out at 206fps or 226 km/h
targetbutt is correct — The actual, real-world speed of an arrow depends on bow design, Draw-weight, whether there is any wind and where it happens to be from (i.e., side, head, quartering, etc), etc, etc. Although targetbutt, you did make what appears to be a mistake: 30 grains is close to the weight of the average .22 bullet (not the whole cartridge, just the lead bullet). I have never heard of any functional arrow point, whether broadhead or field point, stone or metal, which weighs a mere 30 grains (unless it’s for one of the Wee Folk of Irish legend).
My arrows are approx 560 grains (36.288 grams), and launched from my 50 lb draw-weight longbow with 29-inch draw, probably fly around 180 fps (or approx 123 mph/198 kph) on a windless day. (I have seen some compound-users chrono their under-weight arrows at up to 360 fps/579 kph)
But since this ~2 gram arrow is for a physics equation, we’ll let it slide.
edited to respond to the “real arrow” statement: Any arrow which is actually capable of doing what arrows are intended to do — i.e., kill an animal, pierce a target or whatever — is a REAL arrow. The only “fake” arrows I know of are those designed to be only looked at. I have some of those “stick and things” arrows, and believe me, they are very real; I’ve used them on rabbits many times.