# Centripetal Force: At what RPM must you gainer at to decapitate yourself?

1. Apr 11, 2010

### groinsmash

Ok, here's a question I've been worrying about recently:

If you were to be rotated about your waist, at what rotational rate would your body begin to tear apart, specifically decapitation?

Basically, I've been doing lots of gainers (running back-flips) and I'm concerned that if I get really good at them I might accidentally decapitate myself.

Assume the force required to achieve decapitation is between 5000 and 6000 N (refer to http://en.wikipedia.org/wiki/Hanging#Long_drop for information about this number).

Here's some other information (you may or may not need it...).

Height: 180cm​
Weight: 75kg​

Also, assume the gainer is perfectly laid out and not in tuck or pike position.

As a corollary to this question, find out if Guile's Flash Kick in Street Fighter 2 is feasible without decapitation (assume tips of feet are travelling at the speed of sound). If it is not feasible, find out the tangential velocity Guile's head would be delivered to the enemy and also the force imparted on the enemy (assume Guile's head weighs 4kg and the collision is completely inelastic).

2. Apr 11, 2010

### Staff: Mentor

Just plug in the numbers and see:

Fc = mω²r

Solve for ω. The mass of your head is probably about 5 kg.