Answer to Question #304767 in Physics for jay

Question

A box-shaped metal can has dimensions 7 in. by 12 in. by 3 in. high. All of the air inside the can is removed with a vacuum pump. Assuming normal atmospheric pressure outside the can, find the total force (in lb) on one of the 7-by-3 in. sides. (Enter the magnitude.)

Answer 1

The force is

$$F = pA$$

where $p = 14.7lb/in^2$ is the normal pressure, and $A = 7\times 3in^2 = 21in^2$ is the area of one side. Thus, obtain:

$$F = 14.7lb/in^2\cdot 21in^2 \approx 309lb$$