course phys 202
Dr. smith: I hope you had a great break. I was going to take this physics test this week because I did not have a chance to take it before break. I was wandering what you meant in an email you sent about having my department head filling out a proctor imformation form and the simple procedures that you would send me. I was wandering where on the website I can find the form and if there is anything else I need to do. I also had about 2-3 questions on practice test questions that I could not figure out...
1. Analyze the pressure vs. volume of a 'bottle engine' consisting of 4 liters of an ideal gas as it operates between minimum temperature 290 Celsius and maximum temperature 480 Celsius, pumping water to half the maximum possible height. Sketch a pressure vs. volume graph from the original state to the maximum-temperature state and use the graph to determine the useful work done by the expansion. Then, assuming a monatomic gas, determine the thermal energy required to perform the work and the resulting practical efficiency of the process.
What is the pressure if the system is held at constant volume?
What is the highest water column that could be supported at this pressure?
What pressure would be required to support a water column of half this height?
What temperature would be required to achieve this pressure in the system?
If the system is then raised to the maximum temperature, without increasing the pressure, how much would the gas expand?
The system would displace a volume of water equal to the expansion, and the water would exit at the half-max height. What therefore would be its change in gravitational PE?
What does the pressure vs. volume graph look like?
What is the area beneath the pressure vs. volume graph?
2.A monatomic gas in a 1.5-liter container is originally at 28 Celsius and atmospheric pressure. It is heated at constant volume until its pressure has increased by .48 atm, then at constant pressure until the gas has increased its volume by .72 liters. How much thermal energy is required? By how much does the internal energy of the gas change? How much work is done in the process?
What temperature change is required to raise the pressure by the given amount?
What temperature change is then required to increase the volume by the given amount?
How many moles of gas are originally in the containter?
What is the molar specific heat at constant pressure (denoted C_p)?
What is the molar specific heat at constant volume (denoted C_v)?
How much energy is therefore required for each process?
How much energy goes into the KE of the particles in the system?
How much work is done (i.e., what is the area beneath the P vs. V graph)?
3.Water flows from a container through a hole in the side. At a certain instant the water level is 1.1 meters above the hole, and all the water above the hole can be considered to be descending at 4.3 m/s, while the water below the hole can be considered stationary. What is the pressure just below the hole?
Compare a 1.1 m above the hole to a point at which water exits.
What do you know about P, v and y (pressure, velocity, altitude) at the first point?
What do you know about P, v and y (pressure, velocity, altitude) at the second point?
Use this information with Bernoulli's equation and see what it tells you.
I've broken each problem into a number of parts. Submit a copy of this document with your best answers and your best thinking about those questions, and I'll respond accordingly.
Note that some of these questions are related to the Bottle Engine experiments (assigned as video experiments to be viewed), and that the Measuring Atmospheric Pressure experiment is also related to some of these questions.
The Proctor Information Form is found at http://vhcc2.vhcc.edu/dsmith/Proctor_Information_Form.htm .