The two 60-cm-diameter cylinders in Figure P13.15 , closed at one end, open at the other...

The two 60-cm-diameter cylinders in Figure P13.15 , closed at one end, open at the other, are joined to form a single cylinder, then the air inside is removed.

a. How much force does the atmosphere exert on the flat end of each cylinder?

b. Suppose the upper cylinder is bolted to a sturdy ceiling. How many 100 kg football players would need to hang from the lower cylinder to pull the two cylinders apart?