A machinist bores a hole of diameter 1.35 cm in a steel plate that is at 25.0o C. What is the cross-sectional area of the hole (a) at 25.0o C and (b) when the temperature of the plate is increased to 175o C? Assume that the coefficient of linear expansion remains constant over this temperature range.

Solution to 21E Step 1 -2 Diameter of the hole=1.35cm =1.35x10 m 0 Initial temperature =25 C =298.15K -5 0 -1 Coefficient of linear expansion of steel =1.2x10 ( K ) CSA of hole = r 2 Step 2 (A) CSA at T=298.15K -3 2 2 A= x(6.75x10 ) m A=1.431x10 m -4 2