The old Samson trick

[beautifulduckweed]

You guys ever see that old strongman trick in which the dude pulls a bus or a train using a hitch tied to his hair?

I was always somewhat impressed as a little kid; I wondered why their scalps weren't torn off. I have a fairly sensitive scalp, and the thought of that much tugging on my hair made me wince. As I grew older, I knew there were basic physics principles at work, but I wasn't sure what. However, early this morning, I finally figured it out:

1. The most important thing is this: attach the hitch to a huge clump of hair. I can't remember which exact scientific principle is at work here, but essentially, while it's easy to pull out one, two, or even a few dozen strands of hair out by the root at the same time, the force required to yank out the hair goes up exponentially the more hair you add. Something about the way force is distributed along each individual strand? (vyrin, redsouffle or ccarrico, you guys know how this works off the top of your head?)

(I was completely unaware of how that turn of phrase would read in context when I first wrote it. Man, how awesome is my unconscious brain? Muy awesome.)

2. The second most important thing: attach the hitch near the root of the hair. Hair gets much more brittle towards the tip and breaks much more easily.

3. Start the motion slowly and gradually. A rapid yank hurts and the rapid acceleration could create enough force to cause real damage, but gradual acceleration creates a force that feels like...pressure. It's not necessarily pleasant, but it's bearable.

4. The rest is essentially back and leg strength, and getting the head at the correct angle so that you transfer the force down along the spine instead of wrenching your neck. It's still a fairly impressive feat of strength, mind you, but the pulling-by-hair is a bit of distracting flash; it essentially works like a harness in this situation.

Science is nifty.

Comments

[nebula1500.livejournal.com]

I would imagine pressure is the key word. Pressure is force/area, so if you put a force on one hair, the area is tiny, so the pressure is huge. But if you use that same force and spread it out over an entire head, the pressure isn't so bad.

So I don't think that it's any harder to pull out 100 hairs than it is 1, it's just that you would need a much higher force to make up for the larger area.

It's the same reason you can lay on a bed of nails and be fine, but lay on one nail and you're... screwed?

[rat-bastird.livejournal.com]

bah!

You're friend beat me to it!

I had a physics teacher that demonstrated this by putting a board with nails on his chest and then having another teacher bang it with a sledge hammer.

If I hadn't liked him, i would have been praying for a slip for my own personal amusement.

If you have 1 hair and it takes 5lbs of pressure to pull, disperse that over 100 hairs, you'd need 500lbs, and then 200 hairs you'd need 100lbs.

I'm not sure the lb per pressure you'd need, but you get the point.

Physics is cool. Maybe I'll take that as my next class for something fun and relaxing. Accounting is NOT fun.