# Automatic Hair Comb Question

goldliger
Hey guys!

I've got an OTF comb (a.k.a. "out the front," where the plastic hair comb "blade" ejects straight out from the handle) that is held in the closed position with 1 lb, 12 ounces of magnetic force. I.e, upon measuring it takes 1 lb, 12 oz. of finger pressure against the comb switch to eject the comb *automatically*. The plastic comb "blade" itself weighs 1 oz.

Basically, I'm wondering how one would go about determining whether this is a reasonably secure configuration -- and by "secure" I mean - what would it take to have the comb eject from the handle accidentally while being carried in the pocket) considering the plastic comb "blade" will be carried in the pocket and generally tip pointed down (within the handle, of course). I've done rudimentary testing such as jumping up and down, stomping, shaking my pockets, etc, with this automatic comb in my pocket - pretty much everything short of jumping off a 100 foot cliff with rock slab at the bottom...

Any ideas, mathematical formulas, etc, are most welcome, and thanks for your time!

Homework Helper
2022 Award
Since it takes 16+12= 28oz of force to eject the 1oz blade it would require an acceleration of 28 gees (28 times gravity). This is the impact acceleration required to set off an airbag...

Mentor
Hey guys!

I've got an OTF comb (a.k.a. "out the front," where the plastic hair comb "blade" ejects straight out from the handle) that is held in the closed position with 1 lb, 12 ounces of magnetic force. I.e, upon measuring it takes 1 lb, 12 oz. of finger pressure against the comb switch to eject the comb *automatically*. The plastic comb "blade" itself weighs 1 oz.

Basically, I'm wondering how one would go about determining whether this is a reasonably secure configuration -- and by "secure" I mean - what would it take to have the comb eject from the handle accidentally while being carried in the pocket) considering the plastic comb "blade" will be carried in the pocket and generally tip pointed down (within the handle, of course). I've done rudimentary testing such as jumping up and down, stomping, shaking my pockets, etc, with this automatic comb in my pocket - pretty much everything short of jumping off a 100 foot cliff with rock slab at the bottom...

Any ideas, mathematical formulas, etc, are most welcome, and thanks for your time!