Electronics 10 zhong: Lab 5: Kinetic Theory and PV Diagrams

We started the day by describing the state variables that best describe the status of a gas, which are pressure, volume, temperature, and the number of moles of atoms in the gas.

Then we talked about the four thermodynamic processes, Adiabatic, Isobaric, Isothermal, and Isochoric, then we worked on some examples from ActivPhysics.

For question 1, we chose the positive linear slope because in Isobaric process, the pressure is constant, and using the ideal gas law, we get V = T. Both are directly proportional with constant pressure.
For question 2, we also chose the same graph, because in Isochoric process, the volume is constant, so we have P = T.
For question 3, we picked the inverse function graph since temperature is constant in Isothermal processes, so we have P = c/V.
For question 4, we read wrong the question; therefore, we only explained what will happen if the temperature decrease, so as T decreases, the volume will also decrease since the pressure is constant in Isobaric process, so they have a direct relation.

For question 5, the volume is constant, so when the temperature increases, the pressure also increases.
For question 6, the temperature is constant, so when the decreases, the pressure increases due to the inverse relationship.

This picture shows that Adiabatic and Isothermal graphs are different.

We worked on an exercise that consisted of lifting a mass with a rubber band, and what will happen if we heated it up. We said, if the rubber band is heated up, then the rubber band will compress. We later watched a video where a blow dryer was used to heat a rubber band with a hanging mass.

We worked on the can lifter can-do exercise. Here is a detailed procedure of what the system does.

We also noted that a machine will never reach 100% efficiency, simply because is impossible in real life since not all heat energy is converted into work, and some of them escape to the outside.

Then, we worked on "A heat engine using a simple gas cycle." First we wrote down all the information give, then draw the graph of the cycle. We determined the work done by the gas and the work done on the gas, by referring to the graph. Also we showed where QH and QC belong in the graph.

Later, we calculated the internal energy on each point in order to find the change in internal energy for each transition.

With the results we got from the change in internal energy, we were able to calculate the work and the heat transferred in each transition.

Professor Mason conducted an experiment called "The incredible mass lifter engine." In which a flask connected to a syringe is put in cold water. Then measure the volume and pressure of the syringe. Then put an eraser on top of the syringe in order to increase pressure and decrease volume. Then heat up the flask by changing it into a beaker filled with hot water to cause a change in pressure and volume as the temperature increases. Finally, after the syringe went up, take off the eraser and let it cool down.