Googlemapsflow

Googlemapsflow t1_itznpjt wrote

Reply to comment by BasedOnAir in TIL that flight recorders must be able to withstand an acceleration of 3400 g for 6.5 milliseconds and that this is roughly equivalent to an impact velocity of 270 knots (310 mph; 500 km/h). by IchBinKoloss

to stop over a time period of 6.5msec implies that it stops over a distance. I calculated velocity over the given 1.5ft distance and it was a different impact speed. The real answer is that they reported a max velocity when speed calcs are performed assuming a half sine wave impulse. Meyer explained it to me in a different comment

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Googlemapsflow t1_itt4wor wrote

Reply to comment by meyerpw in TIL that flight recorders must be able to withstand an acceleration of 3400 g for 6.5 milliseconds and that this is roughly equivalent to an impact velocity of 270 knots (310 mph; 500 km/h). by IchBinKoloss

Thanks Meyer, that makes sense. A half sine wave averages about 0.63 of peak acceleration and 485mph x 0.63 gives right at 310mph. I'm open to literature on this if you have any recommendations

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Googlemapsflow t1_itt3p5n wrote

Reply to comment by Tankeverket in TIL Amedeo Avogadro's contribution to chemistry, known as Avogadro's law, did not initially receive much attention when he published his paper in 1811. It was only a century later that his work was recognized, when the King of Italy attended a meeting commemorating the paper's 100th anniversary. by dustofoblivion123

Jeez, read the article. In his other, less well known paper he said "I won't feel like I've really made it until Italian royalty recognizes my contribution."

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Googlemapsflow t1_itstq0e wrote

Reply to TIL that flight recorders must be able to withstand an acceleration of 3400 g for 6.5 milliseconds and that this is roughly equivalent to an impact velocity of 270 knots (310 mph; 500 km/h). by IchBinKoloss

3400g is equivalent to 3400g where g is the acceleration due to gravity, g = 32.174 ft/(sec^2). 3400g's is an acceleration. By assuming the entirety of the impact is 0.0065seconds, and assuming the final velocity (V_f=0mph), we can solve the initial velocity (V_i) algebraically with the kinematic relation: at=V_i-V_f

This can be rewritten as: a*t=V_i V_i=(3400 * 32.174fpss)*0.0065s= 707.2 feet per second

there are 22fps/15mph, so

V_i = 707.2fps * 15mph / 22fps = 484.8mph

I got an impact velocity of 485mph and I'm not sure how I got it wrong.

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