Post by thread:[EE]: Oscillator leads

(retagged) | / |/ /-------- / excess \ lead |\ \-------- | \ > Your physics doesn't add up. If "all the energy" goes into the > excess lead, it will presumably be converted to kinetic energy > of that lead causing it to fly off. Alan's "shockless" certainly looks like an ultra-flush cutter. I've found mine to be a lot gentler than the dual bevel type, and cut-offs just drop away, rather than fly off. Could be something to do with the sharpness/hardness of the blade, but whatever, you don't get the impression of any force going back towards the PCB I don't know if this analogy holds water, but how about a shaped explosive charge or guillotining charge. This is also wedge- shaped like the above ASCII and directs all the explosive force into the beam or whatever's being cut without sending much energy the other way -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

| / |/ /-------- / excess \ lead |\ \-------- | \ > > <- no force cutter force applied -> > Your physics doesn't add up. If "all the energy" goes into > the excess lead, it will presumably be converted to kinetic > energy of that lead causing it to fly off If the leftmost edge is perpendicular to the lead and remains so during the cut surely it can't impart any horizontal force in the leftward direction ? -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> >> Your physics doesn't add up. If "all the energy" goes into the >> excess lead, it will presumably be converted to kinetic energy >> of that lead causing it to fly off. Well, OK. How about "half the energy" goes into the excess lead, and (the equal and opposite) half goes into the board. The board goes flying off in the opposite direction, about 0.1 mm due to its relative mass... :) Barry -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.

> Well, OK. How about "half the energy" goes into the excess > lead, and (the equal and opposite) half goes into the board. > The board goes flying off in the opposite direction, about > 0.1 mm due to its relative mass... :) It doesn't quite work that way either. Since both masses receive the same impulse and assuming they both start in the same intertial reference frame, the velocity imparted on each will be inversely proportional to its mass. Energy is proportional to the square of the velocity, so the kinetic energy received by each mass is proportional to the inverse of the square of the mass. This means the vast majority of the energy will go into the snipped wire like you said in the first place. I wasn't objecting to that portion of your statement. I've had experience trying to teach basic physics to college freshmen and have seen the general confusion, so I always try to respond whenever someone plays fast and loose with things like energy, momentum, velocity, impulse, etc. These all have precise meanings. ******************************************************************** Olin Lathrop, embedded systems consultant in Littleton Massachusetts (978) 742-9014, spam_OUTolinTakeThisOuTembedinc.com, http://www.embedinc.com -- http://www.piclist.com hint: The PICList is archived three different ways. See http://www.piclist.com/#archives for details.