89. Square Root by the Table.-The same methods as have been explained for cube root can be applied to finding square roots by the use of the table. The only difference is in the case of decimals, in which case the decimal point is shifted by multiples of two places in the number; then, after we have the root, we shift the decimal point back one place for each period of two places that we moved the decimal point in our original number. PROBLEMS The tables are to be used wherever possible in working these problems. 151. What would be the length of a steel sheet from which to make a 28 in. circular drum, allowing 14 in. extra for lapping and riveting the ends? The circumference of the drum is measured in the direction of the length of the sheet. 152. The small sprocket of a bicycle contains 8 teeth, the large sprocket 24 teeth. The rear wheel is 30 in. in diameter. Find the distance travelled over by the bicycle for one revolution of the pedals. 153. The diameter of a 13 in. bolt at the bottom of the threads is 1.16 in. What is the sectional area at the bottom of the threads? 154. A No. 000 copper trolley wire has a diameter of 0.425 in. What would be the cost of 1 mile of the wire at 33 cents a pound? 14" FIG. 35. in. thick and 60 in. diamFind weight of plate. 155. A circular piece of boiler plate (Fig. 35) eter has an elliptical man hole in it 14 in. by 10 in. Note.-Area of an ellipse = .7854 Xa Xb, where a and b are the long and short diameters of the ellipse. 156. The paint shop wants a cubical dip tank built to hold, when full, 400 gallons of varnish. What will be the dimensions of the tank? (There are 231 cu. in. in a gallon.) 157. How many square feet of galvanized iron will be needed to line the tank of problem 156 on four sides and the bottom, allowing 10% extra for the joints? 158. A high carbon steel contains the following items in the percentages given: Carbon, .60%; silicon, .10%; manganese, .40%; phosphorus, .035%; sulphur, .025%. The rest is pure iron. Calculate the weights of carbon, silicon, manganese, phosphorus, sulphur, and iron in one ton (2000 lb.) of the steel. 159. I want to get a cast iron block 18 in. long and of square cross-section so that it will weigh 200 lb. How many cubic inches of metal must be in the block and what will be its dimensions? If we 160. Fig. 36 shows a steam hammer having an 8000 lb. ram. assume that this ram is a rectangular block of steel, four times as high and twice as wide as it is thick, what will be the dimensions of the ram? FIG. 36. |