PSI

Pounds Per Square Inch

Pounds / Square Inch

It’s a measurement of pressure. A Force divided by an Area.

If you weigh 200 pounds, and the bottom of your shoe has an area of 20 square inches, then standing on your two feet would exert 200 pounds / (20 square inches * 2) = 5 pounds/square inch.

If you are talking about a floor, think of a floor made of thin ice, of glass, of tile, and of wood. Each of these can withstand different pressures. Standing on the thin ice would easily break it, the glass could crack, but the tile and wood could be fine.

You can also think about changing the size. Lets say I switch the two shoes to two peg legs. The end of each peg leg is only one inch square. Now each peg leg is exerting 100 pounds per square inch.

Or I get the point even sharper so it’s 0.1 square inch. Now I’m exerting 1000 pounds per square inch on the floor.

If I’m holding a pencil and pushing the eraser into the palm of my hand with 10 pounds of force, that’s not going to do much of anything. But if I take a needle and push it with 10 pounds of force it will go right into my skin because the pressure of 10 pounds on a tiny area is enough to break my skin.

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