• Archive through May 23, 2008 May 23 - 06:50 am [20]

(typing on a BlackBerry sucks)

what is this? kung fu physics?

Thanks people esp Shane. Very useful answers.
Like you said (and bob#2 witily insinuated in other threads) better work out these questions by doing it.

This is a queer sorta triathlon: weights,taichi,boxing.

Can't help over thinking esp about physics. They trained me to design bridges.

ta
RJ

Tim: I don't think the whip statement is correct. If it became stiff, it would stop 'cracking' in the middle of the crack as the crack soundwave is from the motion of the tip. And it is contrary to my experience cracking whips.

Mark: I think you misread Tim's statement. He's saying the whip stays soft- but the chi produced feels hard as steel.
In the 70s, I was quite good at whip work. I could remove a cigarette from a toddler's mouth at 20 paces.

Bob#2

Never cracked whip before, but here's a review article of a paper on whipcracking physics.
It suggests that it's the loop, not the tip, that produces the cracking.

Beware though; this was the result of a numerical model.

http://www.nature.com/physics/highlights/6890-2.html

rj

Bob #2: That's damn good, I was never able to flick a cig from a todlers mouth past 14 paces.

can a whip crack in space?

Robert. The simple answer is no, however, theoretically, enough random particles might be moved to produce some incredibly small sound. Not likely however.

What does Mrs Adam Smith think?

random particles? hmmm.

i wonder if the strength of the wave would be amplified in space due to less resistance

Robert, Yes, might be, but it is the tip of the whip moving at supersonic speed which results in the air 'cracking'. It is breaking the sound barrier. Not much air up there.

if a whip cracked in outerspace and there was no robert would it make a sound?

Of course whips crack in space and make sound.

it SOUNDS like robert means- if a whip cracked in OUTERSPACE would it make a sound?
yes.

what he is implying is if a whip cracked in a vacuum of space- could it still create a vibration- that creates sound.
the answer is yes,
otherwise the whip would not be cracking, it would only be whipping.

BOB Tai Chi Tse Say:
mixing Chi and western physics creates a vacuum in your head- whipping up a frenzy of silly posts

Superstiffness has nothing in common with the cracking of a whip in any meaningful way. It is a neuromuscular phenomena that has beenseen in many elite atheletes from almost every sport. It basically deals with the ability to cause enormous stabilizing contractions at the moment of force production from a complete relaxed state and then return op that state. At the moment of impact, the body "stiffens" all the joint involved with that production of force starting with the lumbar spine. In this way, force from the preceeding movment is transfered into the target.

It would be more like if you had a chain on a handle and on the handel a button that turned the chain into a rod. If you hit something with the chain and at the moment of impact you turned it into a rod then quickly turned it back to a chain you would get the huge imact of a rigid stick and the follow-through and whipping action of the chain.