Q. In a railway track, two rails are joined end to end with a gap in between them because__:
Answer: accidents due to expansion in summer can be avoided.
Notes: 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. The contraction of rail lines does not pose any threat of accident but the expansion does because it leads the te bending of rail lines.