Questions on Expansion and Contraction
Q3. Consider this diagram of a bridge over a river.
(a) Briefly explain why you think one end is constructed on rollers.
This allows the bridge structure to expand when the weather is warm without experiencing resistance to the increase in size.
(b) When would you expect the gap indicated in the diagram to be biggest - in the wintertime or the summertime? (Explain why you think this would be)
In the summertime the average temperature would be higher therefore the bridge would be bigger as it would have expanded from its winter size. The gap would therefore be smaller in summer and largest in the wintertime.
(c) What do you think would happen if the bridge had been constructed with no gap? (Give an answer for construction in midwinter and then one for construction in midsummer).
If it had been constructed in the winter with no gap, the expansion that it would undergo in the summer would make the bridge buckle.
If it had been constructed in the summer with no gap, the contraction it would experience in the winter would make the bridge shrink and have a gap on each bank... pulling it from its fixings.
(5 marks)
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