Final answer:
Cracks and deformations in structures are often caused by thermal stress as materials expand and contract with temperature changes. Sufficient expansion joints and slack are crucial to prevent damage from these forces.
Step-by-step explanation:
Cracks and deformations in structures like railroad tracks, roadways, and frame rails are usually caused by thermal stress due to changes in temperature. As a result of thermal expansion and contraction, materials can undergo stress leading to weakening over time. Forces and pressures created by thermal stress can cause these materials to buckle or crack if they lack sufficient expansion joints or if a change occurs in the cross-section of materials, creating a weak point.
For example, on hot days, railroad tracks and roadways may buckle if they aren't equipped with enough expansion joints to accommodate the expansion of materials. Similarly, power lines sag in the summer and can snap in cold weather without sufficient slack. In homes, plaster walls can show cracks as temperatures fluctuate, and glass cooking pans can crack if they undergo rapid or uneven cooling, all due to differential contraction and the stresses it induces.