Any Physics expert in the house?

Ravenswood · Post by **Ravenswood** » Sun Jan 13, 2008 12:08 pm

I was trying to explain to a commenter on one of my whip videos how the crack of the whip never seems to be nearly as loud without something around for it to reflect off of.
Has anyone else here experienced the phenomenon of being in an open field, and having the sound of the crack seemingly stifled as a result?
Its ponderous to me why this would be the case, but it has been my expereince every single time. Any theories or explanations?
BTW, you can see the video in question on my youtube channel, youtube.com/toastyplatters. It's the one called "Whip Crack Echoes".
Best Regards all,
Ravenswood

Shtick · Post by **Shtick** » Sun Jan 13, 2008 12:18 pm

I think it's because the soundwaves of the crack are moving in a direction away from you (provided you crack it correctly

). It's similar to a train passing you, and blowing the whistle after it passes. You can still hear it, but the soundwaves are more compressed (hence, more powerful) in the direction of travel.

I tried cracking my whip at the beach (tough to find a nice open spot in a city where people won't complain), and I couldn't hear it at all when I faced the water. But when I turned towards the houses on the shore, I definitely heard it.

Shtick · Post by **Shtick** » Sun Jan 13, 2008 12:24 pm

He also mentions Adam's videos. He missed a point or two. First, Adam's cracking in front of a large hill. If you only hear echos off smooth flat surfaces, then how come you can hear echos in a canyon? Also, we don't know what's just out of camera range. There may be a large object.

Secondly, We hear what the camera hears, not what Adam hears. The cracks are louder when directed at the camera than away (see Bernie's videos as well).

Ravenswood · Post by **Ravenswood** » Sun Jan 13, 2008 1:42 pm

Thx pschtyckque

yeah, cracking it towards the ocean is the best example I can conjure up for this instance. And yeah, the whip seems to have an ULTRA directional characteristic to the sound. Thanks for your response, this is quite a fascinating subject!

McFly · Post by **McFly** » Sun Jan 13, 2008 1:55 pm

Good explanation, Chris! Think of the whipcrack like a bat's / dolphin's sonar. If there's something for it to hit, it'll come back to you. But if you aim it off into nowhere, it'll disappear.

Shane