Think critically...
Q7. Bridges are made from materials that contract and expand as the temperature changes, so
they cannot be fastened firmly to the bank of a river or lake. The photographs below show an
expansion joint at the end of a bridge in winter and in summer.
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(A)
(B)
Which season is shown in each picture? Explain how you know?

Metals are known to often expand due to different factor. For example, the rails of a railway are known to often expand in summer and they tend to contract in winter. This tend to make the gaps kept to be between successive rails and it is one that allow for expansion.

Note also that in Summer the expansion joint will tend to have little space as the two sides of the bridge is said to expand because of the heat and in terms of winter, it contract and there are bigger space as they tend to contract in the cold.

Hence, The season that is shown in the picture attached is that:

For the red - summer
For the black - winter

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