3/9/15 - Four Thermodynamic Processes and Engines

A list of variables that can affect thermodynamic processes of ideal gasses.

We did some problems from an online resource for physics and it had us work out problems involving the different thermodynamic processes.

Based on the shape of the curve, we identified the type of thermodynamic process it came from.

Our predictions of a water bottle attached to a rubber band that was to be heated with a hair dryer. We found that due to the organic chemistry of the rubber, it had actually shrunk when heated.

Out introduction to engines and a visual representation of the work done by an engine.

Our designs for a can lifter using a rubber band engine. 4 step cycles that repeats, and we identified the parts of the cycle that produce the work and have work done on them.

The standard equation of efficiency, also the Carnot efficiency. 

A very simple cycle of a 4 step engine. Points 1 to 4 have the pressure and volume known.

Here we identified where the gas is doing and receiving work. The general equation of work done by gasses is also present.

Here is where we identified the heat transfers into and out of the gas.

Given the above pressures and volumes, we calculated the internal energy at every step and the change of energy to the next step.

The same data, but now in a table with the work done at specific steps calculated as well. We found the heat added or lost at each step from the first law of thermodynamics and given that we found the internal energy at each step as well.

A overview of all our data; and we calculated the net work done, giving us the work done by the engine.

Finding the area of the rectangle in the pressure-volume graph gives us the same result that we had calculated.

The same piston setup from the previous class, except this time we're actually using it do some work on an object.

The setup without Tej in the way.

An object, the eraser, is going to be lifted by the piston when the air inside the beaker is heated.

The air expanded and lifted the eraser.

When the eraser was removed, the pressure on the piston head decreased, so it rose higher than before the eraser was removed.

Our volume verses pressure graph for the eraser lifting engine.

Given that we have the values at all four points of the cycle, we can calculate the internal energy at each step, and therefore find the heat added or removed and work done. 

The final values that we found for the eraser lifting engine.