surface. 6" FIG. 79. 40. Finding the Diameter when th Sometimes we know the area of a cir the diameter. This operation is th finding the area when we know the as finding the square root is the rev To find the diameter from the area .7854 and extract the square root o A = the area and D = the diameter e area of a 6-in. circle (6-in. radius). Find weighs 10 lb. per sq. ft. of the pressure per sq. in. piston? (Divide the tot to get the area.) What is 29. A 12-in. pipe is to What must be the diamet area is the same as that c 30. A rectangular fan o nected to a circular duct same as the area of the fa the circular duct? 31. A circular duct in a rectangular outlets 8 in. X the duct so that its capacit of the five outlets? Ea 32. Four stationary stea one steam "header." a 6-in. pipe. What must that its capacity will be e the four 6-in. pipes? (M combined area of the four 33. What is the diame following areas: 63.6 sq. sq. in.? 34. The total pressure c 6780 lb. What must be th per sq. in. is to be 50 lb.? FIG. 81. 36. The fire area through the tubes of a 1 sq. ft. If there are to be 373 tubes, what n eter of each tube? If the thickness of the % in., what standard size tube would you 37. The high-pressure cylinder of a Co diam. The low-pressure cylinder has twi pressure cylinder. Find the diameter of th 38. How far does a 72-in. driver travel in 39. Find the circumference, area in sq. in weight in lb. of a %-in. steel plate 24 in. in d 40. How much more will it cost to enclos the form of a square than in the form of a cts. per ft.? 41. From a piece of sheet iron 3 ft. long four discs each 10 in. in diam. How man sheet are left if no allowance is made for los 42. It is desired to purchase a site for a ro date twenty locomotives. For each locomo ft. is allowed. What must be the diame required? 43. If a locomotive has 82-in. drivers an what is its speed in miles per hr., allowing fo What distance apart are t angular distance between 26 Sq.In. 0 Ia locomotive is to be 6.25 Corliss engine is 18 in. in close 1600 sq. ft. of land in ong and 2 ft. wide are cut many square inches of the loss in cutting the discs? a roundhouse to accommomotive an area of 1000 sq. meter of the circular plot Ling 200 r.p.m., 46. Find the circumfere weight in lb. of a 4-in. stee 47. In Fig. 82 the distan center of the driving whee stroke of the engine? If min., find the correspondin 48. What length of iron for a tank 6 ft. 4 in. in dia |