Kansas Mechanical Journeyman Practice Test

The formula for calculating a BTU (British Thermal Unit) is based on the specific heat capacity of water. One BTU is defined as the amount of heat required to raise the temperature of one pound of water by one degree Fahrenheit. Therefore, the formula correctly reflects that BTU is calculated using the weight of the water in pounds multiplied by the temperature change in degrees Fahrenheit.

Using weights allows for the incorporation of the specific heat properties of water, which is the medium most commonly referenced in heating and cooling calculations. This distinction is crucial because different materials have varying specific heat capacities, and using pounds as a measurement aligns with standard units for BTU calculations in heating and air conditioning systems.

Other options may suggest alternative factors or measurements that do not conform to the established definition of BTUs, such as using volume instead of weight or using degrees Celsius instead of Fahrenheit, which are not applicable in this context of BTU calculation.