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Steel bars, each of length 3.0 m at 28°C, are to be used fo...

Steel bars, each of length 3.0 m at 28°C, are to be used for constructing a rail line. If the linear expansivity of steel is 1.0 x 10-5°C, what is the safety gap that must be left between successive bars if the highest temperature expected is 40oC?

A.

1.2 x 10-1cm

B.

8.4 x 10-2cm

C.

7.2 x10-2cm

D.

3.6 x 10-2cm

E.

1.8 x 10-2cm

Correct answer is D

Gap ΔL = αL1Δθ = 1.0 x 10-5 x 3 x (40 - 28)
= 3.6 x 10-2