Thermodynamics - Heat Engines

Question 1

heat

Answer 1

• When you add heat energy to an object, it (usually) causes the temperature to increase, which means the molecules of the object move faster. Since molecules have a mass, when they are in motion they have Kinetic Energy (1/2mv2). So energy added by heat goes (at least partly) into the KE of the molecules. If you add up the KE of all the molecules in the object, that is called the “Internal Energy U.” For a diatomic gas (one whose molecules have two atoms, like N2, H2, O2, etc.)

Question 2

heat engine

Answer 2

• a system that converts heat or thermal energy—and chemical energy—to mechanical energy, which can then be used to do mechanical work. It does this by bringing a working substance from a higher state temperature to a lower state temperature

Question 3

2nd law of thermodynamics

Answer 3

• states that the state of entropy of the entire universe, as an isolated system, will always increase over time. The second law also states that the changes in the entropy in the universe can never be negative

Question 4

carnot efficiency

Answer 4

• The most efficient heat engine cycle is the Carnot cycle, consisting of two isothermal processes and two adiabatic processes. The Carnot cycle can be thought of as the most efficient heat engine cycle allowed by physical laws.