I have deliberately altered the iconic 1980’s Devo song title to make a point…no, a PLEA! Listen up. Hollywood - “whips do not make their whipping sound by being struck on the floor!”
But that’s all you ever see on TV or in movies. OK, it’s time for me to science this up a bit. The whip-cracking sound comes from the high velocity the tip of the whip (known as the popper) has achieved, and is explained by the law of the conservation of momentum. Your standard bullwhip has a wooden handle and braided leather plaiting over a long continuous core. When you swing the whip over your head and straighten it out in front of you, you send a loop down the length of the whip. This loop is only traveling around 40 mph at first, but since the whip is constructed to get gradually thinner and lighter as it moves out to the tip, the loops velocity increases as it moves down to the popper. My eight-foot trick whip, a short whip perfect for the tight spaces I sometimes perform in, gets that popper moving at over 1000mph. Now, the speed of sound is 760.9 mph, so the brushed-out-nylon popper is actually breaking the sound barrier. The loud pop that you hear is a mini sonic boom. All of this is absolutely true!
The end of the popper itself weighs about a quarter of an ounce, but if it hits you when it moving at 1000 mph it’s going to HURT! I can personally attest to this. I had to learn how to crack a whip when I joined the cast of the Tony-Award winning musical “Barnum”. So, before rehearsals started I bought a Bullwhip and went every day to the only place safe and private enough to practice – the roof of our apartment building in Boerum Hill, Brooklyn. I was up there one day, shirtless, and I was practicing the side crack that I needed to learn for the show. As I cranked up a really big one, a strong wind gust hit me and the whip cracked along my naked back. Now I knew the workers in the brass bed factory across the street were watching me as they worked, and I didn’t want to show any signs of the excruciating pain I was in, so I calmly and stiffly wrapped up the whip and descended the ladder into the building. As soon as I was out of sight I yelped and writhed and cursed in a way that was more appropriate for the moment.
I eventually put the whip into my stage act and performed it injury free for 20 years. I added a couple of blindfolds to make it more interesting.
So, let me close with an admonishment to film and TV makers everywhere – as much as you might enjoy the visual of dirt flying up from the ground when your actor whips his whip, it is more scientifically correct to show it cracking in the air – or on a naked back on a rooftop in Brooklyn.