Aweight of 18,000 lb is supported on a rectangular base plate that is 9 in. wide and 2 ft long. the base plate rests on a concrete slab. determine the stress that the base plate exerts on the concrete slab. express your answer in units of (a) lb/in.2 and (b) lb/ft2. (precision of 1 for (a) and of 1000 for (b))

We want to find the area of the plate in square inches and square feet.  
1) Here we need inches. The area is 9in * 24in =216 in.^2., since 1ft = 12in. 18,000lb / 216 in.^2 = 83lb/in.^2  
2) Here we need feet. With 12 in = 1 ft, 9in = .75ft. The area is .75ft * 2ft = 1.5 ft.^2 
18,000lb / 1.5 ft.^2 = 12,000lb/ft.^2

B) raising the temperature and reducing the volume of the gas.|-/