FLUID MECHANICS AND THERMAL PHYSICS
Go to: HEAT AND KINETIC THEORY
Go to: AP FREE RESPONSE PROBLEMS
FLUID MECHANICS
For problems involving density and specific gravity:
1. Use information given in the problem to calculate the object's mass and volume.
2. Determine the object's density and the object's specific gravity by dividing the object's density by the density of water.
For problems involving Pascal's principle:
1. Complete a data table with the information given, identify which quantities are related to the input and which relate to the output conditions.
2. Use the concept of pressure in a fluid and Pascal's principle to solve the problem.
For problems involving Archimedes' principle:
1. Complete a data table with the information given.
2. Determine the volume of the object from its mass and density. The volume of the object equals the volume of the fluid the object displaces.
3. Use Archimedes' principle to determine the buoyant force.
4. For a floating object the buoyant force equals the object's weight. The weight of the fluid displaced equals the buoyant force.
For problems involving the rate flow equation and the equation of continuity:
1. Complete a data table listing the cross-sectional area of the closed pipe at each point, as well as the velocity and density of the fluid at the each point in question.
2. Use the rate flow equation and equation of continuity to solve the problem.
For problems involving Bernoulli's equation:
1. Complete a data table listing the pressure, velocity of the fluid, and height of the fluid above a reference point for each point in question. If the problem involves a fluid moving through a closed pipe, then determine the cross-sectional area of the closed pipe at each point in question.
2. If necessary, use the equation of continuity to determine the velocity of the fluid at a particular point.
3. Use Bernoulli's equation to solve the problem.
HEAT AND KINETIC THEORY
For problems involving linear expansion:
1. Complete a data table with the information given.
2. Determine the change in length. The final length is the sum of the original plus the change.
For problems involving the ideal gas law equation:
1. Complete a data table listing the absolute pressure, volume, temperature (in Kelvin), and the number of moles of gas present.
2. The absolute pressure equals the gauge pressure plus the atmospheric pressure.
3. Use the ideal gas equation to solve the problem.
4. If more than one gas is present, it may be necessary to determine the partial pressure exerted by each gas. The total pressure equals the sum of the partial pressures.
For problems involving the kinetic theory of gases:
1. Complete a data table listing the absolute pressure, volume, temperature (in Kelvin), an the number of moles of gas.
2. Solve for the average kinetic energy of the gas molecules.
3. Solve for the root-mean-square velocity of the molecules.
THERMODYNAMICS
For problems involving PV diagrams:
1. Identify whether the process is isobaric, isothermal, isochoric or adiabatic.
2. Use the appropriate equation(s) to complete a data table of pressure versus volume.
3. Use the data table to construct the PV diagram.
4. Use the technique of graphical integration to determine the work done during the process.
5. Use the ideal gas equation, the equation for the internal energy, and the first law of thermodynamics to complete the solution of the problem.
For problems involving the Carnot engine:
1. Complete a data table that includes the input and output heat, the input and output temperatures, the efficiency, and the useful work performed.
2. Use the equations for Carnot efficiency and the first law of thermodynamics to solve the problem.
THERMAL PHYSICS AP FREE RESPONSE PROBLEMS
The list of problems is given as follows:
Year of examination
Problem number
Topics covered in problem
1983, 4, PV diagram, first law of thermodynamics
1984, 3, calorimetry, power
1985, 4, calorimetry, conceptual molecular kinetic energy and entropy
1986, 5, Carnot efficiency, power, energy-mass calculation
1987, 3, calorimetry, power
1989, 4, PV diagram, first law of thermodynamics
1990, 4, PV diagram, first law of thermodynamics, ideal gas law, efficiency
1991, 3, heat engine, power, calorimetry
1995, 5, heat engine, power, efficiency
1996, 7, ideal gas law, pressure
2000, 6, experiment design to determine the specific heat capacity of a liquid
2001, 6, gas laws, thermodynamic processes
