# Shared Flashcard Set

## Details

Thermodynamics, Electric Forces, and Electric Fields
Exam 1
40
Physics
02/09/2011

Term
 Temperature
Definition
 the measure of the average KE (translational only!) of the molecules of a substance
Term
 Heat
Definition
 energy transfer due to a difference in temperature
Term
 50°C = ____K
Definition
 Tc=Tk-273.1550=Tk-273.15Tk=323.15K
Term
 500°F ̴ _____K
Definition
 500F=250C250C=Tk-273.15Tk=523.15K
Term
 Zeroth Law of Thermodynamics
Definition
 If 2 substances are in thermal equilibrium with a third, then the two substances are in thermal equilibrium
Term
 Three Gas Laws
Definition
 Boyle's Law, Charles's law, and Gay-Lussac's Law
Term
 Boyle's Law and example
Definition
 Pα1/VAs plunger moves down, pressure increases and volume decreases, temp is constant
Term
 Charles's law and example
Definition
 VαTheating up or cooling down a bottle of soda, pressure inside is constant
Term
 Gay-Lussac's Law and example
Definition
 P α Trecording pressure and temperature readings in a container of water that is heated, iced, and at room temp
Term
 First Law of Thermodynamics
Definition
 If a system undergoes change from an intial state to a final state, where Q is the energy transferred to the system by heat and W is the work doen on the system, the change in internal energy of the system is ΔU:ΔU= Uf-Ui = Q+W (energy input=energy output)
Term
 Second Law of Thermodynamics
Definition
 No heat engine in a cycle can absorb energy from a reservoir and use it entirely for the performance of an equal amount of workORWhen energy changes form, useful energy is ALWAYs degraded to non-useful energy
Term
 What do the laws of thermodynamics mean?
Definition
 Ist--you can't get something for nothing2nd--some energy must always be lost to the environment
Term
 Three properties of charges
Definition
 1.Two types of charges (+ and -)2.Charge is conserved (can't be created or destroyed)3.Charge is quantized (has to be an integer)
Term
 How are neutral objects charged?
Definition
 Conduction(conductor(negatively charged) brought in contact with insulator(neutral charge)) or Induction (almost same as conduction, but no contact only repulsive forces)
Term
 Insulators
Definition
 All materials where charge does not move freely in response to an electric force usually neutra, but become charged when rubbed by charged materials (conductors)
Term
 Conductors
Definition
 materials in which electric charges move freely in response to an electric force
Term
 Coulomb's Law
Definition
 F=k(q1)(q2)/r^2this establishes the fundamental law of electric force between two stationary charged particles--magnitude of electric force F between charges (q1 q2) separated by a distance r
Term
 Mass and Charge of an electron, proton, neutron
Definition
 Electron:mass=9.11x10^-31charge=-1.6x10^-19Proton:mass=1.67x10^-27charge=1.6x10^-19Neutron:mass=1.67x10^-27charge=0
Term
 Compare and contrast electric forces v. gravitational forces
Definition
 Both are capable of acting through space, producing an effect even when there isn't any physical contact between objects involved. However, electric forces are exerted on any other charged object within an electric field. The force is exerted by the field and gravitational force is the mutual force of attraction between two objects.
Term
 Gravitational Field
Definition
 ḡ=Fg/Mo
Term
 Electric Field
Definition
 Ḕ=Fe/qo
Term
 The electric field of a point charge is...
Definition
 away from positive, towards negative
Term
 What are electric field lines?
Definition
 NOT material objects, they are a pictorial representation of the electric field at various locations
Term
 Electric Flux
Definition
 ɸe=EAcosΘaka a net number of E field lines intersecting a surface
Term
 Gauss's Law
Definition
 The only way to have a net number of E field lines intersecting a surface is to have a net charge inside the surfaceGL=electric flux=q(enclosed)=E=kq/r^2
Term
 Dangers of putting a closed can of beans on the fire
Definition
 If the bean can's volume is constant, then the can could explode. When you raise temperature, you also raise pressure which is stated by Gay-Lussac's Law P is proportional to T
Term
 Purpose of expansion joints in buildings
Definition
 They compensate for various changes in dimensions (V) with variations in temperature (T), also known as thermal expansion
Term
 Car mechanics put less air in tires during the summer than in the winter, why?
Definition
 Ideal gas law--all are proportional, so during summer and increase in temperature would mean an increase in pressure. To keep tires from blowing, the mechanic may decrease the volume by putting less air in, in order to allow for an increase in pressure.
Term
 Why is a car safe during electrical storms?
Definition
 Because the charges on the metal shell of the car will reside on the outer surface of the car, and the person inside the car touching the inner surfaces is safe.
Term
 Why does one's hair stand on end during an electrical storm?
Definition
 The net charge of the air is higher during the electrical storm, so the attractive forces between the arm hairs and the air are greater, arm hairs are charged by induction
Term
 Why does a charged comb pick up bits of paper?
Definition
 The comb is charged, and attracts bits of paper because of the displacement of charges in the paper (polarization)
Term
 Which way does air flow during the winter if the door is left open?
Definition
 Heat moves from a source of high temp to low temp..moves from inside to outside (heat engine)
Term
 What does temperature measure?
Definition
 the average kinetic energy of the molecules of a substance
Term
 Compare the electric forces and accelerations for the charges of a proton and electron places in identical electric fields
Definition
 the electric force on the proton is equal in magnitude to the force on the electron, but in opposite direction. The magnitude of the acceleration of the electron is greater than that of the proton.
Term
 3 ways in which heat is transferred
Definition
Term
 How doea a refrigerator work?
Definition
 Works by a heat pump operating in cooling mode, energy is extracted from the interior of the refrigerator and delivered to the warmer air in the kitchen as energy
Term
 What is a heat engine?
Definition
 mechanism that takes in energy by heat and partially converts it to other forms (ME)
Term
 Absolute Zero
Definition
 Basis for the Kelvin scale, equivalent to -273.15 celsius, gives a representation for lower bounds for physical processes lowest possible temp where a substance transmits no thermal energy
Term
 1st law of thermodynamics, in relation to humans
Definition
 humans do work (run, lift, walk, etc),and the internal energy of the body decreases, we replenish this by chemical potential energy stored in foods
Term
 kinetic theory
Definition
 takes molecules and the relationships between pressure, temperature, and volume of gases and says that energy is conserved in all collisions of particles (conservation of matter)
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