Question

If you know the amount of air pressure exerted on a tabletop, how can you calculate the force exerted on the tabletop

Answer 1

First, let's say air pressure is in the dimensions of pounds per square inch.

pounds
------
in^2

And you want to know the force in pounds

You have to figure out what dimension(s) will cancel out dimensions you are not interested in.

pounds = pounds / in^2 * what?

you can see that a "what?" of in^2 will cancel out:

pounds = pounds / in^2 * in^2

pounds = pounds * in^2 / in^2

pounds = pounds.

So, if you can figure what the "what?" in in^2 you'll have the answer.

The area of a surface of often expressed in units of length squared, such as in^2.

So, if you know the air pressure in pounds per square inch and the area of the table top in square inches, you can multiply the two together and get the pounds of force on the table top.

Answer 2

Multiply the air pressure by the area of the tabletop