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Old March 10th, 2010, 18:59   #66
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Let me give this a try. Not a science guy and i havent touched physics since high school. Please correct me if i'm wrong.

volume of sphere:
V= 4/3 * pi * radius ^ 3

1.27m fall
1" = 0.0254 metres

Volume of sphere is .00007m^3

Mass of sphere is 7700 * .00007 = 0.539kg

Potential energy formula is E=Mass * Gravity * Height

0.539*9.81*1.27 = 6.71 J

error. i measured diameter. Radius is .0254metres / 2 therefore volume is 0.00001m3
mass is 7700 * 0.00001 = 0.077kg

0.077 * 9.81 * 1.27 = .9593 J

Originally Posted by Scarecrow View Post
I can't really speak to impact energy - you'd have to account for what part of the trajectory the impact occurred at as the projectile loses velocity and energy as it travels to it terminal destination. Keeping in mind all these discussions are energies calculated at point blank range.

Lets stick to the topic please. I'm trying to keep this thread marketing neutral.

With the 407fps-500fps ranges coming in, and heavier weights with hard BB materials, perhaps we should be revisiting our assumptions about eye protection? Just a thought.

One thing I'd like to mention is I use eye protection at my workplace, and if our eyewear sustains, *any* visible damage, the eyewear is considered compromised and we get a new pair of glasses. That's Occupational Health and Safety (OHSA) talking. The assumptions of post-damage eye protections continued capability to protect post impact I think should also be revisited.
Sorry about digressing off topic, Yes eye protection should be revisited. I have never shattered the lenses of safety or shooting glasses, but the frames, arms easily break at 1j and backyard distances. At 30ft 1j impacts can push the eye pieces out of the WileyX framed SG-1 "goggle". Not enough to damage the lense but enough force to dislocate the fit of the frame to lenses.

Calculating impact energy is a huge headache, it would be great if everyone had a impact chrono but that's not going to happen. If we assume that muzzle velocity is constant to the travel time then we can make some good safe assumptions about safety.

A thought about safety. FPS limits in Alberta to my knowledge go like this

Edmonton ~400 limit AEG
Red Deer 430 limit AEG
Calgary 420 limit AEG.
Do you know what ruins airsoft?
(Chair), (Drama), (Air), (Sugar) softers, filthy casuals
Originally Posted by mcguyver View Post
it would appear I am not first up in this gang-bang
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Last edited by Azathoth; March 10th, 2010 at 19:23..
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