36. You may want a waterbed, but waterbeds are not allowed in your building. Apart from the danger of flood if the bed should puncture or leak, the weight is an issue.
Suppose that a queen-size waterbed mattress is 80 in. long by 60 in. wide by 12 in. high, and water weighs 1kg/L. How much does the water in the mattress weigh in pounds?
If the weight of the mattress and frame is carried by four legs, each 2 in. by 2 in., what is the pressure, in pounds per square inch, on each leg?
How does the pressure on the legs of the waterbed compare with the pressure that a person exerts on his or her feet—for example, a 130-lb person with a total foot area of about one-quarter of a square foot in contact with the ground?