Question

A mechanic bores a hole of diameter 1.35 cm in a steel plate at a

temperature of 25 ℃. What is the cross-sectional area of the hole

(a) at 25 ℃?

(b) when the temperature of the plate is increased to 175 ℃?

[Coefficient of thermal expansion of steel = 1.2 × 10

-5 K

-1

]​

Answer 1

Answer:

a) The area (4u) of the hole at a temperature of 2 C is described

follows

Ao-rx

Where r=-0 0.675 em. Hence

Ao= a x (0.675 cm)

A-1-431 eu

b) In problen (20), we have proved the following relation

AA =(20) An A

(1) Which could be written as folkows

A-Ao-(20) Ao AT

A (2a) Ao AT +Ap

A-Aol+ (20) A7

Where a for the steel is (1.2 x 10( C°)l) and A= 1.431 cu?. Henoe

A=(1.431 en )1 + (2x 1.2 x 10 C'))x [175 25 C

-1-436 c?

RESULT:

a) Ao= 1.431 cm2

b) A = 1.436 cm2