How is specific heat defined in thermal processes?

Specific heat is defined as the amount of heat needed to raise the temperature of a unit mass of a substance by one degree Celsius (or one Kelvin). This concept is crucial in thermal processes, as it allows for the calculation of heat transfer within materials in response to temperature changes. Each substance has its own specific heat capacity, which influences how much energy is required to alter its temperature.

Understanding specific heat provides insight into how different materials react to heat input. For instance, metals, which typically have lower specific heat values, heat up and cool down quickly compared to materials like water, which has a high specific heat capacity and can absorb significant amounts of heat without a large change in temperature.

In the context of the provided choices, the other options do not correctly encapsulate the concept of specific heat. The total heat energy in an object or heat loss to the environment relates to broader thermodynamic principles but do not specifically refer to the measurement of heat per unit mass per degree of temperature change. Meanwhile, the heat needed to change the temperature of gas is too vague, as it does not specify the necessity of considering a unit mass or the degree of temperature change, which is central to the definition of specific heat.