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MU PHY 182 - Exam 1 Study Guide
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PHY 182 1st EditionExam # 1 Study Guide Lectures: 1 - 9Lecture 1 - Pressure - the ratio of the force to the area on which the force is exerted (P=F/A)- Standard atmospheric pressure is defined as 101,300 Pa or 1atm.- The change between two different states of matter is known as a phase change.- State variables are parameters used to describe a macroscopic system (volume, pressure, mass, thermal energy, etc.)- A value you may need to know how to calculate is number density. This is found by dividing the number of atoms within a substance by its volume- On the Kelvin scale, absolute zero is 0K. Absolute zero is defined as the temperature at which the internal energy of a substance is zero.- A system at its melting point is said to be in phase equilibrium, which means that any amount could be solid and any amount could be liquid.Lecture 2 - To perform calculations involving ideal gases, we will use an equation known as the ideal gaslaw: PV=nRT, P is pressure in Pascal, V is volume in m^3, n is the number of moles, R is the universal gas constant (8.31 J/mol*K), T is temperature in Kelvin- For a thermometer to measure temperature, it must be in direct contact with the body. As a result of this contact, the two will reach a state of thermal equilibrium. (So you're actually finding out the temperature of the thermometer, not the body.)- Zeroth law of Thermodynamics: If object C is in thermal equilibrium with objects A and B, then A and B are in thermal equilibrium with each other.Lecture 3- Be sure to remember important energy equations such as K=Wc+Wdiss+Wext- Heat (Q) is defined as the energy transferred in a thermal interaction, it is not a quality of anobject or substance.- Positive work: force causes object to speed up; system's energy increases- Negative work: force causes object to slow down; system's energy decreasesLecture 4- Heat is transferred as a consequence of a temperature difference between two interacting objects. Larger temperature difference=more heat transferred- A thermal interaction is defined as the process by which energy is transferred via atomic-level collisions.- An adiabatic process is one in which no heat energy is transferred between the system and the environment.- The first law of thermodynamics states that a change in thermal energy is equal to the work done + heat transferred.- Heat of transformation (L) is defined as the heat energy that causes 1kg of a substance to undergo a phase change (Q=ML). The value of "L" is different depending on the type of phase change that is taking place.Lecture 5- In a gas process where neither pressure nor volume nor volume are held constant, heat and change in temperature are not directly related, you must use Q=ΔEth-W to solve for heat.- A gas's molar specific heats depend on if it is a monatomic or diatomic gas. In both cases, the difference between the two specific heats is always the same, 8.3, which is also equal to R (the universal gas constant).- The heat added to or removed from a system during a process depends on the PV diagram path.- If a gas is compressed during an adiabatic process, its change in temperature will be positive. If a gas is expanded, its change in temperature will be negative.Lecture 6- If you have two systems, both with all the same initial conditions and one goes through an isobaric process and one goes through an isochoric process, the isochoric system would have a higher final temperature.- Since the change in thermal energy is the same for all processes that have the same change in temperature, we can write that ΔEth=nCvΔT. Note that this equation can be used for all ideal-gas processes, not just isochoric processes.- An adiabatic process occurs when either the system is thermally isolated or the process is performed very quickly.- Heat can be transferred through conduction, convection, or radiation.- Convection is the movement caused within a fluid by the tendency of hotter and therefore less dense material to rise, and colder, denser material to sink under the influence of gravity that leads to the transfer of heat.Lecture 7- Water is a unique substance because from 0°C to 4°C, it gets more dense. Then, after gettingheated past that point, it gets less dense (as a normal substance would).- The temperature at the bottom of a deep body of water will be 4°C.- The high specific heat of water is the reason why large bodies of water cause nearby climates to be more temperate.- The change of momentum of a gas particle = 2m|V|- The total molecules inside of a cylinder = (N/V)(A |V| dt)- The number of collisions in a given time "dt" is equal to the total number of molecules divided by two.Lecture 8- The amount of heat transferred is equal to the change in translational kinetic energy (no work is done so all heat goes into changing Ktr).- For a constant volume process, Cv=3/2 R. This approximation is very accurate for monatomic gases. However it is less accurate for diatomic gases and much less accurate for polynomial gases.- A monatomic gas molecule has 3 degrees of freedom (only translational velocity). - A diatomic gas molecule has 5 degrees of freedom (translational and rotational velocity).- A molecule of an ideal monatomic solid has 6 degrees of freedom.- The speed that is normally calculated for a gas is the average of the speeds of all the molecules in the gas.Lecture 9- When two objects have reached thermal equilibrium, it means that they have the same temperature and the same average translational kinetic energy.- It is not possible for a heat engine to have 100% efficiency. This means that Qc (the heat given off by the system) will never be zero.- The second law of thermodynamics provides and explanation for why thermodynamic processes proceed in a certain way.- Entropy is a state variable; it is the measure of the "disorder" of a system.- The analysis of entropy is how we can tell which way a process will naturally


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MU PHY 182 - Exam 1 Study Guide

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