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44 Cards in this Set
- Front
- Back
- 3rd side (hint)
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speed of sound is inversely proportional to:
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The square root of density
(the lower the density, the faster the travel) , but bulk modulus dominates |
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speed of sound is directly proportional to:
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The bulk modulus
(the elastic component)... s>l>g for bulk modulus Bulk Modulus= (dF/A)/(dV/V) |
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Bulk Modulus=
affects? large for? |
Bulk Modulus= (dF/A)/(dV/V)
stress/strain speed of sound (dir. Prop), compressibility (k is the inverse of bulk modulus) steel>water>gas |
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can sound travel through a vacuum?
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no, only EM radiation (light ) can
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How does temperature affect the speed of sound
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the speed of sound is around 340 m/s, but is faster with higher temperatures because gas molecules move faster to transmit the sound
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How do sound waves travel?
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-Longitudinal
-create areas of compression and rarefraction (decompression) along the axis of travel -molecules themselves do not go with the sound, they just move about an equilibrium position |
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intensity=
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I=PA
[I]= watts/m^2 |
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Thershold of hearing, Io
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1*10^-12 W/m^2
also called the reference intensity and is used in the B equation |
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equation for the sound level, B (in decibels)
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B=10log(base 10) [I/Io]
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Doppler effect
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real( sound +-detector/ sound +-source)
to figure out +- convention, imagine the two on a number line and know that approaching with raise f' and leaving will lower it. |
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units for the doppler equation
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f'=f[(speed of sound+-speed of detector)/(speed of sound +- source)]
everything inside parenthesis is in m/s |
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a police car is moving toward an observer with the siren on: which term should be changed in the doppler equation?
what will the equation be? |
The party that does the work to change the frequency must do the work because adding to the top vs subtracting from the bottom will both increase the apparent frequency, but not by the same amount:
in this case, the cop is doing the work, so change the source term(denominator). the ratio must get bigger |
f'=f(speed of sound/(speed of sound-speed of cop toward deterctor))
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What happens when the doppler effect occurs with light
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red shifts (expanding, moving away, like galaxies)
blue shifts (moving toward you... higher energy/frequency like UV light) |
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open pipe standing wave or string waves fixed at both ends
wavelength= |
lambda= 2L/n
n=1,2,3,4 corresponding to harmonics |
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closed pipe standing wave wavelength
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lambda=4L/n
n=1,3,5, corresponding to harmonics |
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which harmonic is the fundamental one?
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the first harmonic, n=1
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which harmonic is the first overtone?
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the next one up
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for a string attached at both ends, the number of antinodes tell you what?
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the harmonic #
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Standing waves: string vs. open pipe: same formulas but differ in that:
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The ends of a strong are nodes and the ends of an open pipe are antinodes
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Closed pipe description
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one end is closed with a node and the other end is open with an antinode (like a clarinet)
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equation involving internal resistance?
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emf= iR+ir
R=circuit resistance r=internal resistance V=IRtot, so voltage increases (counterintuitive)... emf=i(r+R) |
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What will be the internal resistance of an ideal ammeter?
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zero Ohms... we want to measure current, so we want as much as possible to flow through, and not take any other easier path
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What is the internal resistance of an ideal voltmetter?
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infinity ohms. Since voltage increases with resistance, we need to get all the resistance in this one area to measure it all
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e^0=
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1
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ln(1)=
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0
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What stays constant and what changes when a wave goes from one medium to another?
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Frequency will always stay constant when a wave transfers through mediums, but wavelength and speed may change
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What are the three types of radioactive decay
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Alpha (one type)
beta (3 types) Gamma (1 type) |
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What is emitted in Alpha decay?
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An Alpha Particle, or a Helium nucleus He4,2
-The new element will have lost 2 neutrons and 2 protons, leaving an atomic number of inital-2 and a mass number of initial-4 |
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What side of the equation is the alpha particle on?
the alpha man in lost is the healer |
He4,2 is on the product side because it is lost from the nucleus
He4,2 is emitted. the alpha male in lost is the healer --> alpha decay is loss of a helium nucleus |
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Why does Beta decay occur?
betas like to nip |
Beta decay occurs when the nucleus is unstable due to having too many neutrons (a high n:p ratio)
Betas like to nip Beta decay is n-->p |
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What is emitted in Beta decay?
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A neutron becomes a proton, so an electron is made and emitted to preserve conservation of charge
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What side the symbol for beta decay and what side of the equation is it on?
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a neutron turns into a proton:
on the reactant side: N0,1 because mass number (n+P) is the same, but atomic number (p) is increased by one. On the product side is an electron |
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What will H3,1 become if it undergoes beta decay?
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H3,1 will have a neutron become a proton and emit a new electron to become Helium3,2
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Why does positron emission occur?
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Positron emission occurs when the Neutron:proton ratio is too small. A Proton becomes a neutron and to keep the charge stable, a positivly charged antielectron (positron) is emitted
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What occurs in positron emission?
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A proton becomes a neutron
-atomic number decreases by one -mass number stays the same |
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what is a beta particle?
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an electron emitted when n-->p
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In which forms of decay does atomic number change?
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-In all three forms of beta decay:
products: -gain a proton in n-->p beta decay (betas nip) (electron emission) -loose a proton in p-->n in positron emission (pin up elicit poster ) -gain an electron to make a p-->n to maintain charge (e- guns do this) (pinned by an electron gun) |
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What is electron capture?
capture and cancel pinned by an electron gun |
A type of beta decay
-an electron is captured -a p-->n when +p,-e cancel out |
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What happens to Be7 in electron capture/
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It becomes Li7
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What never changes in the three types of beta decay ?
(beta decay, positron emission, electron capture) |
the mass number!
because p-->n in pos emi/e cap and n--> in beta particle emission, n+p never changes, only atomic number does |
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Which type of decay can change atomic number?
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only alpha decay changes atomic number
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What is gamma decay and why does it occur?
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When an electron is sitting at too high of an energy (such as in the photoelectric effect), it can emit a gamma particle, a high energy photon
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How do 3d/4s subshells loose electrons when a transition metal is ionized?
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the outermost, highest energy subshells loose electrons first (4s before 3d)
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1 angstrom=
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10^-10
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