Talk:Whipcracking

message: last month I've stumbled upon a TV programme about some cowboy festival in America. A lady did amazing tricks with the whip including hitting a penny off the tongue of her partner. `'Míkka 18:41, 30 July 2007 (UTC)
thread_title:  whipcracking tricks 

message: The physics section mentions a vacuum, which is incorrect. The crack comes from the shock wave produced when the whip exceeds the speed of sound, and this does not create a vacuum. I checked the reference for it and it doesn't mention anything about a vacuum either. (Jatoo (talk) 12:55, 8 January 2008 (UTC)
replies: text: don't. - Altenmann >t 03:48, 28 July 2009 (UTC)

text: I know this is an old post. But I assure you it is correct, however counter-intuitive it may or may not be. It can be demonstrated from the kinematics. Mostly for anyone else  who doubts it: Imagine a moving car. The top of the wheel is moving forward with respect to the car at the speed of the car and the bottom is moving backward at the same rate. From a person standing on the ground though, the top is moving twice as fast and the bottom is completely stationary(if not it means the wheel is slipping).--75.80.43.80 (talk) 12:01, 15 April 2011 (UTC)
thread_title:  Physics 

message: This is beyond extremely loud, and would make a cannon sound like dead silence by comparison; See This article and section.  I don't suppose anyone has a more plausible number and a source for it? TJSwoboda (talk) 19:04, 4 June 2009 (UTC)
thread_title:  200 decibels? 

message: At present the article mentions conservation of momentum as the reason for the tip acceleration, however it is actually conservation of energy at play. The distinction is perhaps subtle (both would lead to tip acceleration) but they are different things and would lead to different quantitative result. Source-wise, this PDF (mentioned in an earlier talk topic) explains the crack in terms of energy conservation. Also there is this paper on a related effect for partially falling chains, also explained in terms of energy conservation. (That article is what brings me here. See also related discussion at Talk:Self-siphoning_beads.)
Physics wise I can offer two easy insights. First, there are forces applied between the stationary whip body and the tip, and there is tension all along the body of the whip. These forces transfer momentum between the tip and the person doing the whipping. The forces are oriented such that they decrease the momentum of the tip. Second, if tip momentum p were conserved then the energy (p2/2m) would increase as the tip mass m decreases -- where does this energy come from? In fact it is energy p2/2m that is conserved; momentum decreases as 1/sqrt(m), yet speed increases as sqrt(m). Hence, the crack.
--Nanite (talk) 13:43, 25 October 2014 (UTC)
thread_title:  Physics - Dubiosity on what is conserved 

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thread_title:  External links modified