3/10 Energy Efficiency and Heat Engines

We predict the behavior of the graph of Pressure v. Temperature, Pressure v. Volume, Volume v, Temperature, and what happens when pressure decreases and temperature increases. We answered questions off of a website to solve for Volume, Pressure, and Temperature.

We predict the graphs of Isovolumetric(Isochoric), Isobaric, Isothermal, and Adiabatic graphs. We were then asked why Isothermal is graph B and why Adiabatic is graph D.

This is the prediction for how my group thought the rubber band would behave with a weight hanging below it and when heated with a hair dryer. We predicted that the rubber band would expand but not break but what actually happened was the rubber band shortened.

After seeing how rubber band behaves, we had the question of how a rubber band engine would work if its job was to lift a can off one conveyor belt onto a higher conveyor belt. Each group listed 4 steps required in this process. 

This is a picture of the rubber band shrinking and expanding to transporting the can onto another conveyor belt.

We are introduced to the efficiency of a heat engine and its relationship to work and energy.

We are given a heat engine that has a cyclic process and are asked to find the work done at each of the 4 points and area inside the quadrilateral.

After finding the work done at each point, we calculated the change in internal energy when the process went from point to point. When summed together, the total internal energy is 0J.

This is an example of how a heat engine would behave. The piston at the top would move up and down based on the temperature inside the tube that would change based off if the flask was placed in a cold or hot water bath.

This is the graph of the different points the heat engine undergoes. The shape of the graph should be a closed quadrilateral.

This is a table of what we calculated for the heat engine during each of its 4 different stages.

This is the calculations done for the heat engine experiment in class. We calculated for the heat transfer between each of the 4 points.


Summary: We are introduced to a simple heat engine that is created by quickly changing the temperature of a piston causing the piston to move up and down depending on the temperature. We also calculated for how efficient a heat engine is by looking at the percentage of how much of the heat energy is converted to work. This would give us an exact idea of how much is converted to work and how much is wasted.