How much pressure is caused by a 30 pound weight sitting on a 2 square inch block?

Answer 1

The mass or the weight does not exert the pressure directly. The pressure is the force exerted normally (perpendicular to the surface element) per unit area. Therefore the answer depends not only on the mass or weight but also on the magnitude of the gravity field and the normal degree to which the base block acts to counter that gravity field exertion on the 30 pound mass.

For example, at about sea level on the earth surface and while with no acceleration component in the direction of the gravity, the pressure is 30 lbs / 2 sqr. in. = 15 psi.

On the earth surface, the pressure goes down with elevation decreasing in direct proportion with the square of the height distance from the center (and not from the surface) of the earth.

The acceleration of the system also modulates the pressure. For example, the pressure is zero if the 30 pound mass and the base block both are free falling in any gravity field. Or the pressure is 30 psi, twice greater than 15 psi, when the two are, say, not a rest and not free falling at 1 g acceleration (9.81 m/s sqr) but are stacked straight up in a rocket accelerating straight up from earth sea level at a 1 g acceleration. If, instead, the rocket goes at a 45 degree angle with the earth’s sea floor plane then the pressure is not 30 psi but is only 30 / (2 ^ 0.5) = 21.213 psi.

Answer 2

Pressure is measured in force divided by area. In your case pounds per square inch (psi or lbs/in^2).

So a 30# weight on a 2 in^2 block would be 30# / 2in^2 = 15 psi or 15 lbs/in^2.

Answer 3

15 lbs. psi??

Answer 4

3.75 psi???