**Heat and Thermodynamics **

3.Energy cannot be created or destroyed, although in many processes energy is trans

ferred to the environment as heat. As a basis for understanding this concept:

a.*Students know* heat flow and work are two forms of energy transfer between

systems.

b. *Students know* that the work done by a heat engine that is working in a cycle is

the difference between the heat flow into the engine at high temperature and the

heat flow out at a lower temperature (first law of thermodynamics) and that this

is an example of the law of conservation of energy.

c. *Students know* the internal energy of an object includes the energy of random

motion of the object’s atoms and molecules, often referred to as *thermal energy. *

The greater the temperature of the object, the greater the energy of motion of the

atoms and molecules that make up the object.

d. *Students know* that most processes tend to decrease the order of a system over

time and that energy levels are eventually distributed uniformly.

e. *Students know* that entropy is a quantity that measures the order or disorder of a

system and that this quantity is larger for a more disordered system.

f.**Students know* the statement “Entropy tends to increase” is a law of statistical

probability that governs all closed systems (second law of thermodynamics).

g.* *Students know* how to solve problems involving heat flow, work, and efficiency in

a heat engine and know that all real engines lose some heat to their surround

ings.