Objects are primarily heated by which type of energy?

Objects are primarily heated by radiant energy, which involves the transfer of energy through electromagnetic waves, such as visible light or infrared radiation. This form of energy does not require a medium to transfer heat; it can occur in a vacuum, as seen with the Sun's rays reaching Earth. When radiant energy strikes an object, it is absorbed and converted into thermal energy, thereby increasing the object's temperature.

In contrast, conductive energy refers to the transfer of heat through direct contact between materials. This process typically requires a medium, such as a metal rod heating up at one end when placed in a flame, but it is not the primary way objects are heated in many scenarios.

Convection energy involves the movement of fluids (gases or liquids) and the transfer of heat through the movement of the fluid itself. It is significant in heating environments like air in a room but again, does not cover the direct radiation process involved in heating objects.

Mechanical energy relates to the motion and position of objects and does not pertain directly to the heating process itself. Therefore, radiant energy stands out as the correct answer due to its role in directly heating objects through the absorption of electromagnetic radiation.