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In a railway track, two rails are joined end to end with a gap in between them because
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- steel can be saved
- accidents due to contraction in winter can be avoided
- air-gaps are necessary for bearing the weight of running train
- accidents due to expansion in summer can be avoided.
- steel can be saved
Correct Option: D
The volume of materials changes depending on current temperature. Usually heat makes them expand, and cold leads them to contract. There have to be gaps to avoid strain on the tracks. The same applies in many other fields of engineering, i.e. bridge building.
