Metal rods of length 20m each are laid end to end to form a bridge at 25oC. What gap will be provided between consecutive rails for the bridge to withstand 75oC? [Linear expansivity of the material = 2.0 x 10-5K-1
A. 0.20m B. 0.22m C. 0.25m D. 0.02m
Correct Answer: D
Explanation
Safety gap = expansion of the rod = \(\alpha \times L_0 \times \Delta t\) where \(\alpha\) = linear expansivity of the material \(L_0\) = Initial length of the material \(\Delta t\) = Change in temperature \(\therefore\) The safety gap = \(2 \times 10^{-5} \times 20 \times (75 - 25)\) = \(2 \times 10^{-5} \times 10^3\) = \(2 \times 10^{-2} m\) = 0.02 m
