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प्रश्न
One end of a steel girder in a bridge is not fixed, but is kept on roliers. Give the reason.
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उत्तर
In the construction of a bridge, steel girders are used. One end of the girder is fixed into the concrete or brick pillars and its other end is not fixed, but it is placed on rollers. The reason is that if there is any rise (or fall) in temperature of atmosphere, the girder can freely expand (or contract) without affecting the pillars.
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