kinetic energy formula

[bmfer]

does anybody know the formula for calculating kinetic energy? I had it written down somewhere and its still there.

[robtattoo]

Yep.

Arrow weight in gn X Speed in FPS squared / 64 /7000 gives ft/lb of energy


ie; arrow weighs 600gn, flys at 170fps, so

600x(170x170)/64/7000 = 38.705 ft/lb of KE.

[bmfer]

thank you very much

[**DONOTDELETE**]

I've never seen KE calculated with that formula bfore?????

KE =M x v2 / 450,240
Kinetic Energy=Mass times velocity squared divided by 450,240
ke=Kinetic Energy (ft lbs)
M = mass (weight of entire arrow (shaft, point, vanes, nock,...

That is the weight of your arrow in grains times speed, times speed (in feet per second)divided by 450,240 equals KE in foot pounds. after 17 years of shooting speed bows i know that one well

[Matthew D]

okay the only one I knew of was
KE= 1/2(mass x (velocity)^2)  
Kirk, just curious where did the 450,240 come from?

[strick9]

450240 is the actual constant for the formula, dividing by half or the above formula gets you close but kirklls formula is the correct one as far as physics is concerned.

[buks2hunt]

M x V x V / 450240
Works everytime, may have to borrow some fingers and toes but it works.


Bill

[Bogsucker]

450240 comes from 7000 grains per pound and 32.16 pounds per slug. To get mass you must divide grains by 7000 to get pounds, then you must divide pounds that by 32.16 to get slugs. 32.16 is only used in the KE formula as most of physics now uses 32.17 also The unit for the KE value is inaccurate as it is commonly known as "ft-lbs" it should be slug-feet per second squared.

[Bjorn]

Or, simply use the calculator:
 http://home.att.net/~sajackson/archery.html