Will heating objects generally cause them to expand or contract?

Heating objects generally causes them to expand due to the increase in temperature. When an object is heated, the particles within that object gain energy and move more vigorously. This movement tends to push the particles apart, leading to a greater distance between them and resulting in an increase in the overall volume of the material. This phenomenon is observed across various states of matter, including solids, liquids, and gases.

In solids, while they may appear rigid, the atoms or molecules are still in motion, and heating them increases that motion, causing expansion. In liquids, the increase in kinetic energy allows molecules to move more freely, also resulting in expansion. Gases, which already have particles that are relatively far apart compared to solids and liquids, will expand even more significantly when heated.

Understanding thermal expansion is crucial in many applications, including engineering and construction, where materials must accommodate changes in temperature to avoid damage or failure. Therefore, heating objects generally leads to expansion, making this the correct answer.