A bit of googling found this: 5000 m/sec: speed of sound in structural steel 1500 m/s : speed of sound in water (temp. dependent) 1600 m/s : speed of sound in hydraulic fluid/oil 330 m/s : speed of sound in air (STP) 3e8 m/s : speed of light in a vacuum However, I seem to recall reading some theory in which electrons in a wire are viewed as "marbles in a tube", and thus electricity can apprear to move faster than the speed of light. The theory went that since the "tube" was already full of "marbles", putting one in the end spits one out the other end instantaneously, though no single "marble" really moves that fast. I don't remember the source, but I'll poke around some of my old electronics books and see if I can find it. ----- Original Message ----- From: "John Ferrell" To: Sent: Saturday, June 26, 2004 11:57 AM Subject: Re: [OT] : Challenging...(another thought) > So how much delay is there in a hydraulic system? My intuition is telling me > it is faster that a sonar signal. > John Ferrell > http://DixieNC.US > > ----- Original Message ----- > From: "William Chops Westfield" > To: > Sent: Friday, June 25, 2004 8:38 PM > Subject: Re: [OT] : Challenging...(another thought) > > > > On Jun 25, 2004, at 7:07 AM, Russell McMahon wrote: > > > > > 2. Look at waves hitting a beach or ripples hitting the edge of a > > > pool > > > etc. If the wave front is slightly off square, watch what happens to > > > the > > > contact point as the wave hits the edge or shore. Whiel nothing on the > > > wave > > > moves faster than wave speed, the contact point is related to the > > > arctan of > > > the contact angle. For very small angles, the contact point can travel > > > at > > > speeds of 100's of kilometres per hour when the wave is travelling > > > under 10 > > > kph. Nothing physical is actually moving this fast but the motion can > > > be > > > very clearly observed. > > > > > > There's a similar phenomena for EM/etc; either the 'group velocity' or > > 'phase velocity' of the waveform corresponding to something like a > > fundamental packet; (IIRC, it goes something like this. A particle is > > like a wave, right? but you apply forier analysis to get something > > that looks like the discontinuous waveform of a particle, and the > > individual frequencies involved have to have propagation velocities > > faster than C. > > Unfortunately, you can do anything useful with those parts...) > > > > BillW > > > > -- > > http://www.piclist.com hint: PICList Posts must start with ONE topic: > > [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads > > > > -- > http://www.piclist.com hint: The list server can filter out subtopics > (like ads or off topics) for you. See http://www.piclist.com/#topics -- http://www.piclist.com hint: PICList Posts must start with ONE topic: [PIC]:,[SX]:,[AVR]: ->uP ONLY! [EE]:,[OT]: ->Other [BUY]:,[AD]: ->Ads