Find the number of kilograms needed to pull apart evacuated Magdeburg Hemispheres whose radii are 25.0 cm when the barometer reads 760mm of Hg.
I really don't know where to start. Could someone walk me through it?
The Attempt at a Solution
I read somewhere that an equation to help is F=pi*r^2, so I made 25.0cm into 0.250m, and made F=pi*0.0625... but that doesn't seem right.