So the end of a towel may or may not reach the speed of sound. Does this answer the question of whether the snap is a mini sonic boom? There are other ways to make noises you know.
I think Cecil’s point was “it’s not impossible, nor far-fetched”. However, given that his resources are limited to finding other peoples’ work (he’s not exactly sitting on a gold mine), he can’t go out and do it himself.
I always thought that the “wet-towel snap” was caused by the individual folds in the towel slapping against each other… but hey, I could be wrong.
The link to the Staff Report being discussed is: Is the sound of snapping a towel a sonic boom?
If you are the Original Poster (OP) starting a new topic, it’s a good idea to provide a link to the Staff Report being discussed.
Note that this was NOT done by Cecil hisself, but by Straight Dope Staff Veg. Staff have even less budget than Cecil has.
Yes, the report by SDStaff Veg begs the question: what then DOES cause the snapping sound. We establish that the crack of a whip is caused by the tip breaking the sound barrier. We have evidence of a towel-like object that definitely breaks the barrier. We have evidence that a true towel comes pretty close, consistent with the fact that you don’t always get a snap from snapping a towel. If it isn’t breaking the sound barrier, and creating a mini sonic boom, what IS making the cracking sound?
I think it may likely be the slap of towel tip on towel. If it were creating a sonic boom, why don’t dense dry towels make that crack sound?
lacking a detailed knowledge of the physics of fabrics…I venture to the analogy of hair…wet hair is (or at least seems) longer than dry hair… if this is in fact the case, it would imply that fibers become more stretchy when wet, which would enable for quicker snapping action…also there is the concept of momentum and air resistance… a dry towel weighs less (and thus would be easier to slow down), and has more surface area since everything is “frizzed out” (would be slowed down more by air anyway)…the combination of the two would make the dry towel less likely to reach the high speeds necessary to break the sound barrier.
of course this is all guess-work psuedo-science, but whatever
You’d think by now some would-be Harold Edgerton would’ve captured the snap on film and solved the mystery.
NOTE: Since this appears to have been a link to a site for ordering a commercial CD-ROM, I have severed the link. – CK Dexter Haven, Admin
[Edited by C K Dexter Haven on 07-02-2001 at 01:09 PM]
Take a damp wash cloth rolled like the whip and quickly pull the two ends apart you get a similar crack. This is hardly a mystery.
While conventional wisdom (something I though SD treated with skepticism) would have it that the crack of a bull whip is also a sonic boom I am unconvinced on this point as well. It has certainly been demonstrated that a bullwhip does create a sonic boom however in my review I see no proof that the crack of a whip is a sonic boom rather than a more conventional sound. It is like asserting that a gunshot is a sonic boom based upon the fact that the bullet leaves the muzzle at supersonic velocities while completely ignoring the explosion of the gunpowder.
Part of my problem with the sonic boom theory is the sound seems to radiate like conventional noise unlike a sonic boom which is a wave front travelling in the direction of the object and does not propagate. Consider the sonic boom of a bullet, you don’t hear it until the bullet passes you and if the bullet hits something before reaching you then you don’t hear it at all.
Whips have been filmed at more than the speed of sound but a recent article says it is the lopp on the whip crack that breaks the sound barrier (explaining why it doesn’t occur earlier as the tip can be going at up to twice the speed of sound. http://www.spacedaily.com/news/whipitgood-02a.html
Incidentally the original question is in part answerable as well - there is a martial art from Kerala in South India (called Kalari) which has as one of its disciplines using a thin towel (which travellers would carry) called a “thoth” to hit vulnerable or nerve points using a towel snap. Just like people used to do in school in fact but with more accuracy. Has anyone heard of this?
I am unable to find information about “thoths”. However, this sounds like what was used in a set of books by Glen Cook, the Black Company saga. The Black Company is the first in a set of fantasy stories (running nine books) that follow a mercenary band in their exploits in the fantasy world. The original setting is a Europe analogue, but in the latter books, the group travels to a different continent that is an analogue of India. There the group runs into a mystery sect that appears to be a version of the Kalari mentioned. The sect were secret assassins, and did use cloths as their weapon. However, they did not whip them. Rather, they used them to strangle their victims.
I have no idea how much relation this has to actual practices by Indian groups, but Cook had much depth to his use of Hindu religion (as well as the other religions and cultural elements used).
IIRC, the thuggee cult of India used scarves to strangle their victims, as the ritual was to kill without shedding blood.