# Convert force to psi

If I have something that can lift 400lbs. How would I determine how much pressure this could generate if used in a punch type situation. I would be punching a hole.

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Danger
Gold Member
If I understand the question correctly, you just divide your 400 lbs. by the surface area over which it is applied. For instance, a 1/4 sq. inch punch with 400 lbs behind it would exert 1,600 psi.

Yeah, that was exactly what I was wanting to know. I don't know why I was thinking it was more difficult. Thanks.

Danger
Gold Member
Quite welcome, I'm sure.

Danger said:
Quite welcome, I'm sure.

Actually, that depends on the kind of loading (i.e. static or impact).
It is true that to solve for stress, one only needs to divide F/A.
However, in an impact situation, you force is actually mass times acceleration. Therefore,

Stress = ma/A

(I think)

Danger
Gold Member
The wording of the question sort of led me to think that infraray was considering the use of an arbour press or such-like, so I assumed the impact speed to be negligible. It would be a little more complicated if he were using a gun of some kind, because there'd probably be deformation of the tool head and more heat production. That's a little out of my league.

Actually acording to Newtons second law of motion F=ma and their for ma/A=F/A so it does not mater either way