Question

Heat energy always flows from a body at higher __________ to a body at ________temperature.
A. temperature, lower
B. heat, lower
C. temperature, higher
D. heat, higher

Answer 1

Hint: Heat is among the several forms of energy that tends to flow from a particular system to another. This flow is only possible because there is some difference in the temperature within these systems. Thermal energy or heat always flow from the hotter system to the colder system. The alternate form of second law of thermodynamics states that heat can never flow on itself from a cold body to a hot body. This information can be used to answer this given question.

Complete answer:
If there is a temperature between the temperature of two systems which are in constant contact with each other, the heat will always transfer from one system to another until both the systems are in equilibrium with each other. According to second law of thermodynamics, heat cannot flow on itself from body at lower temperature to a body at higher temperature
Thus, heat energy always flows from a body at higher temperature to a body at lower temperature.

Hence, the correct answer is option A i.e. temperature, lower.

Note:
Students should always remember another name for heat energy is thermal energy and its unit is joules. Temperature is the parameter which measures the flow of heat within the systems by determining the systems net kinetic energy. If heat is to be transferred from a colder system to a hotter system, then the work should be done on the system. But when the heat is transferred from the hotter system to the colder system, it happens automatically and the system performs work.