# Shared Flashcard Set

## Details

Final Exam
Chapter 2 and Chapter 3
129
Physics
12/13/2010

Term
 Speed
Definition
 d/t: units (m/s)
Term
 Distance traveled
Definition
 Speed x time
Term
 Average Speed
Definition
 measure total distance over long time, with speed possibly varying a lot in between
Term
 Instantaneous Velocity
Definition
 Speed right now (speedometer)
Term
 Vectors   Adding a Vector    Subtracting a Vector
Definition
 A physical quantity having some magnitude in a given direction: Velocity, Acceleration, Force    Adding a Vector- In same direction ADD   e.i.- walk 1 m/s down a down escalator going 1 m/s. Your total speed is 1+1=2 m/s relative to fixed ground   Subtracting a Vector- In opposite direction SUBTRACT    e.i.- 100 N force to the right and 50 to the left= 100-50 to the right
Term
 Velocity
Definition
 Speed in direction of travel    Speed or direction    Changes a constant (only constant w/ acceleration) amount per unit time
Term
 Acceleration
Definition
 change in velocity/ change in time   Constant but 0 with velocity    e.i. - forward -- speeding up  - backwards -- slowing down -  @ right angles to the motion-- change in direction or turning
Term
 Force
Definition
 A push or pull in a given direction    Vector- the strength of a push or pull in a given direction.   NET FORCE- every force acting on an object   Unit-- Newton
Term
 Distance
Definition
 Changes at an increasing rate each second (acceleration)   Changes equal amounts in equal times (velocity)
Term
 Free Fall
Definition
 Any object falls to earth with same acceleration   g=10 m/s^2,   in absence of air resistance    e.i. - constant downward acceleration g= 10 m/s^2 - upward velocity slows down - downward velocity increases with time.
Term
 Newton's First Law
Definition
 an object at rest or with constant velocity, fixed speed is   in a straight line (inertial motion)    any object undergoes inertial motion unless acted upon   by a net outside force
Term
 Equilibrium
Definition
 when object has no net outside force
Term
 Static
Definition
 object at rest remains at rest.
Term
 Dynamic
Definition
 object in motion goes at constant velocity
Term
 Newtons Second Law
Definition
 Net force on an object causes the acceleration of that   object proportional to net force, inversely proportional to   mass (m)   a= F_net/m
Term
 Inertia
Definition
 tendency of object to stay at constant velocity   resistance to change in motion is proportional to mass
Term
 Mass
Definition
 amount of  material an object contains (stuff) Units= Kg
Term
 Weight
Definition
 Force of gravity pulling object to earth i s proportional to   its mass. BUT NOT the same as mass!
Term
 Newton's 3rd Law
Definition
 Force acting on object by another always comes with an   equal and opposite reaction by the first on the other.
Term
 Interaction pairs
Definition
 two objects touching each other   e.i.- walking or driving a car: you push back against ground, it pushes you forward   e.i- Rocket: hot gas is pushed out of the rocket. rocket propelled forward by push back of gas
Term
 Weight
Definition
 force of gravity   magnitude mg, pointing down   W= m g    m= object mass   g= 10 m/s^2 on surface of earth.   g on moon much smaller. Things weigh 1/6 as much as on earth
Term
 Support Force
Definition
 force between two rigid objects at their surfaces   preventing their motion through each other.
Term
 Friction
Definition
 rubbing force between two surfaces   e.i: to be at rest, the net force on it has to be zero
Term
 Momentum
Definition
 mass x velocity    p=mv   measures how hard it is to stop an object    cannot change unless object acted upon by outside force
Term
 Impulse
Definition
 p = Force applied times time it's applied    The same can be either large force over short time (hard collision) or small force over large time   (gentle collision)
Term
 Collisions
Definition
 Elastic-- bounce--momentum is conserved and KE   Inelastic--stick--momentum is conserved but NOT KE
Term
 Work on an object
Definition
 Force applied x distance object is moved    Units of work/energy: 1 Joule = 1 Newton x 1 meter   W= (mg) h or weight x height lifted
Term
 Potential Energy
Definition
 energy stored in position (with respect to a force) require   WORK against a force to gain potential ENERGY
Term
 Work
Definition
 1/2 mass x speed squared:   W= 1/2 mv^2
Term
 Kinetic Energy
Definition
 energy stored in a moving object   KE=1/2 mv^2    = total amount of work put into accelerating it   = total amount of work it can do coming to a stop
Term
 Momentum versus KE
Definition
 KE is amount of "damage" an object can do   Momentum is how hard it is to stop   bullet of 1kg going at 100m/s
Term
 Conservation of energy
Definition
 energy cannot be created nor destroyed or lost    if an object is doing no work, and nothing is doing work   on it   its total energy, KE+PE, does not change    PE lost (as you lose height) = KE gained (as you gain   speed)
Term
 Kinetic Energy Lost
Definition
 to friction is not gained as PE! it goes into heat or    thermal energy
Term
 Vibrations (or oscillations)
Definition
 Motion of object goes in repeated cycles
Term
 Period (T)
Definition
 time to go one complete cycle
Term
 Frequency (f)
Definition
 number of cycles completed per unit time   1 Hertz (Hz)= 1 cycle/ second   Frequency is 1/ Period   f= 1/ T
Term
 Resonance
Definition
 driving frequency equals Natural Frequency--frequency at   which an object will   oscillate IF LEFT TO ITSELF
Term
 Wave
Definition
 oscillatory disturbances that travel in some medium,   through space.    sound wave--travels through air
Term
 Wavelength
Definition
 distance from crest to crest or trough to trough
Term
 Frequency
Definition
 time for successive crests to pass by any given point
Term
 Wavespeed
Definition
 depends only on the medium the wave is travelling in
Term
 Amplitude
Definition
 size of displacement caused by wave
Term
 Sound
Definition
 air molecules displaced back and forth
Term
 Transverse Wave
Definition
 displacement of medium is perpendicular to direction of   travel of wave
Term
 Longitudinal Wave
Definition
 displacement of medium is along the direction of travel of   the wave
Term
 Crest + Crest
Definition
 constructive interference
Term
 Crest + Trough
Definition
 destructive interference
Term
 Pitch
Definition
 frequency as interpreted by ear   double frequency-- raise pitch by--octave
Term
 Loudness
Definition
 amplitude squared of displacement of sound wave   change in air pressure detected by ear
Term
 Quality or Color
Definition
 how many overtones sound when a musical note is played   IE how many different frequencies combine to make the   note
Term
 Charge and Electricity
Definition
 Two types--- + and -    Likes repel, opposites attract
Term
 Quantized
Definition
 1 Coulomb (standard metric unit of charge) = charge of    6.25 x 10^18 electrons
Term
 Electrons
Definition
 negative charge, magnitude e
Term
 Protons
Definition
 positive charge e
Term
 Conserved
Definition
 Charge is not created nor destroyed, but transferred by   transmitting electrons from one object to another
Term
 Very Little Net Charge
Definition
 # electrons roughly equals # protons
Term
 Conductors
Definition
 electrons move freely inside   transfer electrons by contact with conductor
Term
 Insulators
Definition
 all electrons bound to atoms   transfer electrons by vigorous rubbing
Term
 Rubbing
Definition
 transfers charge between insulators   one becomes positively charged   the other negatively charged
Term
 Charge  Induction
Definition
 presence of charge near a conductor "induces" charges   inside conductor to travel   opposite charges nearer to outside charge like charges   farther from it.
Term
 Grounding
Definition
 contact with large conductor can remove excess charge   from object.    Earth (if wet) is an excellent ground
Term
 Electric Force and field
Definition
 force between two charges q1, q2   depends on each charge    inversely proportional to distance squared between them
Term
 Electric field
Definition
 "aura" around any charge, its ability to exert force   measures their ability to exert force on other charges
Term
 E= F/q
Definition
 Force on test charge in field/ charge of test charge
Term
 Field lines/ lines of force
Definition
 show direction of E field at any point   spacing gives sense of its strength    point--away from--positive charge   point--towards--negative charge
Term
 Potential
Definition
 work done to move test charge to a position / its charge   V= PE/q   V measured in Volts (Joules per Coulomb)
Term
 Battery
Definition
 maintains  a constant potential across its leads   High potential positively charged, low potential,   negatively charged
Term
 Resistor
Definition
 resists flow of current across it
Term
 Bulb
Definition
 like a resistor, buts emits light
Term
 Voltage
Definition
 change in electric potential across a circuit element   1 Volt= 1 Joule / Coulomb
Term
 Current
Definition
 flow of charge past a given point-- charge flow per unit   time   1 Ampere= 1 Coulomb / second
Term
 Resistance
Definition
 resistance to current flow thru a resistor measured in   Ohms   bulb filament= high resistor    wire= low resistance
Term
 Current
Definition
 Voltage / Resistance (I= V/ R)
Term
 Series
Definition
 Current= Same   Voltage= different
Term
 Parallel
Definition
 Voltage= Same   Current= different
Term
Definition
 R= R1+ R2
Term
 Parallel
Definition
 1/R= 1/R1 + 1/R2
Term
 Power
Definition
 P= Voltage x Current ( P=VI) (Watts= Volts x Amps)
Term
 Magnetization
Definition
 Presence of magnetic field turns iron objects into magnets   themselves
Term
 Magnetic field of a wire
Definition
 a straight wire has a magnetic field that circles it in loops   field proportional to current
Term
 Magnetic field of wire loop (or coil of loops)
Definition
 Field passes through loop and acts like a bar magnet   North pole= field line leave loop    South pole= where field line enter loop
Term
 Electromagnet
Definition
 many wire loops around unmagnetized iron/steel rod.    Current magnetizes iron   Result is much stronger magnet than that current alone
Term
 Force on a wire int he presence of a magnetic field
Definition
 an electric current running perpendicular (or partly perpendicular) to magnetic field to feels a force    perpendicular to field and current   magnetic field DOES NOT WORK
Term
 Electromagnetic MOTOR
Definition
 Converts Electric energy--- mechanical energy
Term
 Induction
Definition
 a change i the magnetic field passing through a wire loop   or coil induces current in the loop
Term
 AC GENERATOR
Definition
 uses magnetic induction to convert   Mechanical energy--Electric energy
Term
 Electromagnetic fields
Definition
 an eletromagnetic whose magnetic field changes creates   AN INDUCED ELECTRIC FIELD in its vicinity
Term
 Speed of electromagnetic wave IN VACCUUM
Definition
 c= 300,000,000 meters/second= 3x 10 ^ 8 meters/second   30 cm every 1 billionth second
Term
 Speed
Definition
 wavelength x frequency= >c    Instantaneous ? of light is always c
Term
 Visible light
Definition
 ROY G. BIV   blue has shorter wavelength than red
Term
 IR
Definition
 longer wavelength than red; "heat" from the sun
Term
 UV
Definition
 shorter than blue
Term
Definition
 very long wavelengths, up to kilometers
Term
 Xray
Definition
 wavelength comparable to atom diameter
Term
 Gamma Ray
Definition
 extremely short
Term
 Light is a Particle or Wave
Definition
 Both    Particle like and Wave-liker properties
Term
 Photon
Definition
 quantum of light    light "particle"   short burst of light energy
Term
 E_photon
Definition
 h x frequency    h--planks constant    blue? more energy than red: X-ray, Gamma-rays very high   energy
Term
 Photoelectric effect
Definition
 high energy UV photons kick out electrons from metal.   Lower energy light photons can't proof of particle nature of light   (energy comes in small bundle rather than spread out everywhere like a wave)
Term
 Intensity/Brightness of light
Definition
 number photons/ unit time
Term
 Emission Spectra
Definition
 analysis of intensity of light of different frequencies
Term
 Spectral line
Definition
 light of one specific frequency seen in emission spectra of   an atom
Term
 Atomic spectra
Definition
 electron emits light, and decays from high energy orbit to low   change in electron energy=hf=photon energy
Term
 Flourescence
Definition
 glow of some minerals in UV light   electron excited by UV light decays back to low energy in smaller energy steps   resulting photons are visible light
Term
 Incandescence
Definition
 glow of black body (eg coals, sun, stove burner)   with temperature   average frequency= temperature of body
Term
 Average speed of light
Definition
 slows down in a dense medium; v=c/n; n--index of refraction,=1.5 for glass
Term
 Fermat's Principle
Definition
 light takes shortest time path going from one point to another
Term
 Reflection
Definition
 ray of light reflected leaves at same angle as it came in: angle in= angle out
Term
 Refraction
Definition
 when entering a slower medium, light bends "in"    when entering fast medium, light bends "out"
Term
 Glare
Definition
 100% reflection when rays strike object at glancing angle
Term
 Sunsets
Definition
 refraction of light as goes from lighter air to denser.   See sun horizon when it has already passed below
Term
 Image
Definition
 a point where light from an object is made converge to or diverge from, by using laws of reflection or refraction
Term
 Prism
Definition
 bends light in same direction at each surface
Term
 Dispersion
Definition
 blue light is slower than red   it is bent more by refraction
Term
 Total internal reflection
Definition
 when light hits a surface from inside a dense medium (e.i. from inside water, trying to got to air) an angle > 45 degrees   100% of light is reflected, 9% is transmitted (passes thru) fiber optics
Term
 Lens
Definition
 used to focus light    focal length of lens   image from distant object is inverted (upside down)   image is real   energy of light is focused at focal point   only part of lens is needed to capture whole image
Term
 Huygen's principle
Definition
 all wave properties can be constructed by looking at light as coming from lots of point sources
Term
 Diffraction
Definition
 light bending around obstacles due to interferences of light in/around the obstacle
Term
 Large wavelengths bend more than  small while ? bend the most
Definition
Term
 Greater bending occurs from small diameter objects than ?
Definition
 large
Term
 Interference
Definition
 combination of displacements of two or more waves when colliding    occurs form any type of wave
Term
 Two slit experiment
Definition
 bright spots occur when constructive interference between light of two slits occurs   Spacing of peaks depends on wavelength    Red peaks displaced more than blue
Term
 Diffraction grating
Definition
 interference from many slits    used as prism. to spread out light of different frequencies
Term
 Soap bubbles
Definition
 example of thin film interferences    interferences of reflected light from front surfaces and back    color depends on which wavelength constructively interferes
Term
 Polarization
Definition
 direction in which wave is displaced as travels through medium    absorbs light, lets other through   converts unpolarized light into ?   crossed -- 100% light absorbed    reflected glare naturally ?
Term
 Transverse waves only
Definition
 light, but not sound
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