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From: Theo Bekkers on 11 Sep 2007 22:41 Yeebok wrote: > Logic (or physics) dictates that the friction created by the wheels > would scrub some speed. Like GB said it's not something I'd have > considered as an impact on decelerating a plane whilst on the ground, > but I would be very surprised if there was no energy moved from 'plane > speed' to 'tyre speed', e=mc^2 etc. From that attitude I hope it doesn't involve putting the nose into the ground. Theo
From: JL on 12 Sep 2007 00:38 Errrm e=mc^2 ? F=MA where A would be the negative acceleration (braking) perhaps ? JL (assuming I'm remembering my highschool physics correctly) On Sep 12, 12:39 pm, Yeebok <per...(a)computer.com> wrote: > Logic (or physics) dictates that the friction created by the wheels > would scrub some speed. Like GB said it's not something I'd have > considered as an impact on decelerating a plane whilst on the ground, > but I would be very surprised if there was no energy moved from 'plane > speed' to 'tyre speed', e=mc^2 etc. > > > > Mr_Han...(a)qnr.com.au wrote: > > GB wrote: > > >> Mr_Han...(a)qnr.com.au wrote in news:vs0de3lje86dcfcfjtqr76609cp0pfvgrn@ > >> 4ax.com: > >>> Yah, I guess it all looks a bit definitive, sorry about that. > >>> Sources are my own study material, small knowledge of fluid dynamics > >>> (applied to unloaded turbines or air driven rotors), conversations > >>> with experienced pilots and instructors, some commonsense... > >>> If you want Internet sources, google has plenty... I used "landing > >>> gear wheel spin", but you can roll your own as you wish... > >>> And I'm certain you will find plenty that contradict what I say :) > >> More than likely! That's the whole point of the intarweb, isn't it?! > > >> It seems logically valid, I'd just never heard the claim made > >> before (and I've made something of a study of things aviation > >> over the years). -2 to -5 knots does seem like a lot... > > > Have a look at your ASI next time you touch down. Even though it's > > generally low off the scale, the needle still drops - significantly on > > bitumen, less so on grass. > > Qualitatively, the figures look OK by me.- Hide quoted text - > > - Show quoted text -
From: Yeebok on 12 Sep 2007 03:19 What does e=mc^2 mean ? energy = mass * speed of light squared. It does not only pertain to thermonuclear explosions. It's an expression of the amount of potential energy contained in an object. Or how about 'for every action there's an equal and opposite reaction' ? Or more simply where does the energy to make the tyres squeal on impact and start to spin (and emit a puff of smoke) come from if not the plane landing ? If it comes from the plane it 'must' decelerate due to the transfer of energy. Mr_Hankey(a)qnr.com.au wrote: > JL wrote: > >> Errrm e=mc^2 ? >> >> F=MA where A would be the negative acceleration (braking) perhaps ? >> >> JL >> (assuming I'm remembering my highschool physics correctly) > > My mind was boggling at the thought of a negative force equivalent to > that generated by a small (or, for that matter, large) nuclear > weapon... > > > Gives a whole new meaning to ABS, doncha think? > > :) >
From: Yeebok on 12 Sep 2007 06:38 Point taken - however being a pedant is sometimes a hassle.. :) Mr_Hankey(a)qnr.com.au wrote: > On Wed, 12 Sep 2007 07:19:17 GMT, Yeebok wrote: > >> What does e=mc^2 mean ? >> energy = mass * speed of light squared. >> >> It does not only pertain to thermonuclear explosions. It's an expression >> of the amount of potential energy contained in an object. >> >> Or how about 'for every action there's an equal and opposite reaction' ? >> >> Or more simply where does the energy to make the tyres squeal on impact >> and start to spin (and emit a puff of smoke) come from if not the plane >> landing ? If it comes from the plane it 'must' decelerate due to the >> transfer of energy. > > Mr Einstein talks about total potential energy, including that locked > up within the atoms that make up the object. > Yes of course, you are quite correct, but for the size of the > action-reaction system we are talking about here, I prefer Mr Newton's > over-simplifications. For a start, the maths are easier. >
From: Kevin Gleeson on 12 Sep 2007 08:04
It wasn't pedantry, it was just totally wrong. Sorry . . . On Wed, 12 Sep 2007 10:38:02 GMT, Yeebok <person(a)computer.com> wrote: >Point taken - however being a pedant is sometimes a hassle.. :) > >Mr_Hankey(a)qnr.com.au wrote: >> On Wed, 12 Sep 2007 07:19:17 GMT, Yeebok wrote: >> >>> What does e=mc^2 mean ? >>> energy = mass * speed of light squared. >>> >>> It does not only pertain to thermonuclear explosions. It's an expression >>> of the amount of potential energy contained in an object. >>> >>> Or how about 'for every action there's an equal and opposite reaction' ? >>> >>> Or more simply where does the energy to make the tyres squeal on impact >>> and start to spin (and emit a puff of smoke) come from if not the plane >>> landing ? If it comes from the plane it 'must' decelerate due to the >>> transfer of energy. >> >> Mr Einstein talks about total potential energy, including that locked >> up within the atoms that make up the object. >> Yes of course, you are quite correct, but for the size of the >> action-reaction system we are talking about here, I prefer Mr Newton's >> over-simplifications. For a start, the maths are easier. >> |