Final answer:
Expansion caused by heating can be useful in preventing damage to railway tracks and roadways, preventing power line breakage, and explaining cracks in plaster walls.
Step-by-step explanation:
One example of the usefulness of expansion caused by heating is the presence of expansion joints in railroad tracks and roadways. On hot days, these surfaces can buckle due to the heat-induced expansion, but the presence of expansion joints allows for the free expansion and contraction, preventing any damage.
Another example is the sagging of power lines more in the summer than in the winter. As the temperature rises, the power lines expand, and without sufficient slack, they can snap in cold weather.
Cracks opening and closing in plaster walls are also a result of expansion caused by heating. As a house warms and cools, the materials expand and contract, leading to cracks.