# Calculating force for animal bites/scratches

1. Dec 10, 2011

### Physics quest

Heya, I am wondering how would one calculate or find the force associated with animals such as tigers, dogs, lions etc.

At the moment, i am interested in finding how much force or pressure is created by a cat when it scratches. Any help would be appreciated, thank you.

As a side note, this is mainly to find out how much, comparatively it takes to cut human skin, rough figuires online point me to about 400 pounds per square inch of pressure required to penetrate human skin but does that literally mean per square inch of skin or is that just a measurement? Do I find the area of a cats claw (somehow, not sure how I would do this, its very small) and then divide the 400 psi down to pounds per square millimeter or whatever the cats claw size is?

Thank you again for any aid.

2. Dec 11, 2011

### JHamm

The pounds per square inch doesn't mean you actually need to take a square inch of skin, just like you don't need to wait an hour for your car speedometer to give you a new reading.

3. Dec 12, 2011

### Physics quest

So when taking smaller measurements, lets say a square millimeter I divide the number for square inch, e.g. 400 for human skin pressure resistance and reduce it by said number, so humans would in my example have only 0.6 psi per square mm?

Then from there, find the force of a cat scratch, probably the hardest bit, probably easier finding a bite or something but ime interested in the scratch because I am interested in the small amount of damage one can produce, wheras bites can become more severe.

4. Dec 12, 2011

### MrB8rPhysics

Using pressure to estimate the force will give you a lower boundary on what he force could be...

Reccomend working in N/m^2 btw rather than imperial units. Saves fiddly conversions.