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Physics 101 flashcards AP® Physics flashcards
1
Q

define acceleration

A

Acceleration is the rate of change of velocity ie an acceleration of 5 ms-2 means the velocity is
increasing by 5 ms-1 every second

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2
Q

what are satelites

A

satelites are in freefall around a planet or star. They are constantly accelerating but not changing speed. this is because of direction, not the magnitude of their velocity is changing. the surface of the planet or star curves away from the satellite at the same rate the satelite curves towards it hence the satelite remains in orbit at a constant altitude

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3
Q

what are the rules for projectiles

A

o The first job is usually to resolve the initial velocity into components (uhorizontal = u cosθ and
uvertical = u sinθ where θ is the angle to the horizontal)

o From now on only use the components uh and uv

o Horizontal velocity is constant (use sh = vh t)

o Vertical acceleration is constant due to gravity (use sv uv vv av t and watch your negatives).

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4
Q

define newtons first law

A

newtons first law states that an object will remain at rest or move with a constant speen in a straight line (constant velocity) unless acted upon by an unbalanced force

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5
Q

newtons second law

A

F = ma.

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6
Q

newtons third law

A

states that for every action there is an opposite and equal reaction. punch a wall and the force of my fist on the wall is equal to that of the wall on my fist

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7
Q

friction

A

force that always acts opposite to an objects motion

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8
Q

tension

A

pulling force, acts both ways at same time

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9
Q

air resistance

A

increases with speed. what makes an object eventually reach terminal velocity

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10
Q

scales in a lift

A

scales measure the force acting upwards on a person

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11
Q

slopes

A

The component of weight acting down a slope = m g sinθ where θ is the angle of the slope
to the horizontal.

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12
Q

define the conservation of momentum

A

states that the total momentum before a
collision/explosion is equal to the total momentum after the collision/explosion as long as no
external forces are acting

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13
Q

what is an elastic collision vs an inelastic collision

A

Elastic collision: Kinetic energy is conserved. Inelastic collision: Kinetic energy is NOT conserved.

in both momentum is conserved

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14
Q

impulse

A

the change in momentum = area under a force time graph. this takes place when there is a net external force. Ns

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15
Q

gravity Qs

A

remember to measure from center of one mass to center of the other

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16
Q

relativity - what is time dialation and length contraction

A

The speed of light in a vacuum is the same for all observers.

Time dilation is the increase in an observed time interval for an object moving relative to an
observer compared to that measured when they are in the stationary frame of reference.

Length contraction is the decrease in the observed length (in the direction of motion) of an object
moving relative to an observer compared to that measured when they are in the stationary frame
of reference.

t and l are when the observer and object are stationary relative to each other, ie they are in the
same location, and t’ and l’ are when there is relative motion, ie things are observed in more than
one location.

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17
Q

Evidence supporting the Big Bang/expanding universe theory

A

Cosmic Microwave Background Radiation
the abundance of hydrogen and helium
the darkness of the sky (Olbers’ paradox) - if universe infinite should be stars in all parts of the night sky
the large number of galaxies showing redshift rather than blueshift.

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18
Q

dark matter

A

the mass of a galaxy can be estimated using the orbital speed of their stars

Masses measured are bigger than those predicted by looking at the number of stars present

conclusion is that there must be matter we cant see - Dark matter

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19
Q

Dark energy

A

supported by the accelerating rate of expansion of the universe ie something appears to be opposing gravity

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20
Q

hotter the star is the

A

shorter the peak wavelength of emitted radiation (more blue)

the more energy it emits per m^2

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21
Q

what is the longest and shortest wavelengths of visible light and what colours do they appear as

A

380 - 700 nm

380 is violet and 700 is red

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22
Q

Standard Model

A

12 Fermions (matter particles)

6 Quarks – up, down, charm, strange, top, bottom

6 Leptons – electron, electron neutrino, muon, muon neutrino, tau, tau neutrino

4 Gauge Bosons (force carriers)

photon (electromagnetic force)

Z and W± bosons (weak nuclear force)

gluon (strong nuclear force)

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23
Q

Hadrons

A

made up of quarks

Baryons are made of 3 quarks eg protons, neutrons

Mesons are made of 2 quarks (a quark and an anti-quark) eg pions, kaons

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24
Q

strong force

A

Strong force holds quarks together and also holds protons and neutrons together in the nucleus

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25
Q

beta decay

A

Beta decay is caused by the weak force and is evidence of the Neutrino

beta minus decay consists of a neutron is affected by the weak force and one of its down quarks turns into an up quark becoming a proton . to conserve charge an electron is emitted aswell as an anti neutrino

beta plus decay - proton affected by the weak force turns into a neutron (up quark turns to down quark). releasing an anti electron (positron) and a nuetrino

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26
Q

what is antimatter

A

particles are identical to their corresponding matter particles except charge. if touches its matter counterpart it is annihalated

27
Q

Eletric field - what way do lines go , what particles will accelerqte and why

A

in diagram lines point from pos to neg

a charged particle will accelerate in an eletric field because it experiences unbalanced forces

gain in kinetic energy = work done by eletric field

28
Q

what is p.d.

A

voltage is the number of joules of energy per coulomb of charge

29
Q

magnetic feilds - what does moving a charged particle do, which way do field lines go

A

moving charged particle will produce magnetic field

field lines point from north to south

30
Q

what is nuclear fusion

A

nuclear fusion is smaller parts combining to a more massive nucleus

whatever mass is not converted is turned into E ——- E=mc^2

31
Q

what is fission

A

big nucleus splitting into smaller parts

induced/stimulated - usually caused by bombardment with nuetrons

spontaneous - random event/no trigger

32
Q

wave particle duality

A

the photoelectric effect is proof that light is a particle

interference proves light is a wave

33
Q

photoelectric effect

A

clean negatively charged zinc plate exposed to high F ultra violet light discharges

each photon of light gives electron energy to jump off

34
Q

light going from vacuum (air) to medium

A

speed wavelength and angle all decrease

F does not change

35
Q

total internal reflection occurs when

A

the angle of incidence is greater than the critical angle

36
Q

irradiance from a point scource follows what law

A

inverse square law
if you double the distance then the irradiance will quarter
if you triple the distance then the irradiance will be 9 times less

37
Q

bohr model of atom

A

Eo is the ground state and lowest E level

E0, E1, E2 etc have negative energy levels in comparison to the ionisation level
‘
ionisation level has an energy of 0 - if electron gain ionisation energy they jump off

electrons gain E and jump up if they go down E they give off photon of light

38
Q

peak and rms

A

peak always bigger rms = peak over root 2

use rms values for power calc

39
Q

parallel and circuit

A

o Current in series is the same (CISS), current in parallel branches add up to supply current

o Voltage in parallel is the same, voltage in across series components add up to supply voltage
(VIPs use VISA …)

40
Q

t.p.d. = terminal potential difference

A

the p.d across the rest of the circuit

41
Q

ideal supplu

A

A SUPPLY with no r

42
Q

open circuit

A

infinite resistance - nothing connected across terminal

supply = emf as no current so no internal resistance

43
Q

short circuit

A

no load resistance and mac current drawn

44
Q

how is r calculated

A

use a variable resistor and plot V on y and I on x

r = negative gradient
emf = y intercept
max current = x intercept

45
Q

if more than one supply

A

combine rs and emfs

46
Q

capacitance is

A

the number of charge stored per volt

47
Q

charge against p.d. graph

A

Gradient = capacitance

area under the graph = energy stored

48
Q

when capacitor is fully charged

A

p.d = supply V
current = zero
V across resistor = 0

49
Q

when Capacitor is fully discharged

A

V = 0
Current = max current allowed by ohms law
V across R = supply V

50
Q

Current does what when charging AND discharging

A

starts large and decreases in magnitude

51
Q

Increasing R or C does what

A

increases the time taken for capacitor to charge and decreases magnitude of max current

increasing C also increases the max energy stored(can also be achieved by increasing supply voltage )

52
Q

when atoms combine what happens to the electrons

A

they combine into energy bands instead of discrete energy levels

53
Q

what are the diffs between the bands

A

the fullest band is the valence band and the band above that is the conduction band.

electrons are held tightly in the valence band but have room to move freely in th econduction band.

54
Q

conductors

A

have overlapping conduction and valence band so dont require energy for electrons to move across bands

55
Q

insulators

A

have a empty conduction band and an full valence band
there is also a large energy gap so the electrons require large amounts of energy to jump up

56
Q

what is doping

A

adding impurities to semiconductors to reduce their resistance

57
Q

what is a semiconductor

A

like an insulator but with a much smaller band gap, the gap is small enough that at room temperature some electrons have energy to jump from valence to conduction band and increase the conductivity of the solid. conductivity increases aka resistance decreases with increasing temperature

58
Q

n-type

A

an n-type semi conductor is one that has been doped with an element with more electrons so there are extra electrons. these are added to the conduction band and allows it to conduct more. makes it negative

59
Q

p-type

A

impurities are added which have extra holes.
this creates gaps in the valence band. this makes it p

60
Q

p-n junction

A

p and n type conductors are side by side. a depletion layer forms which has virtually no free charge carriers.

61
Q

forward and reverse biased

A

forward = n to negative and p to positive

reverser means opposite

62
Q

solar vell

A

is an unbiased p-n junction. photons enter and give electrons enough energy to jump from valence band of p type to conduction band.
moves down to the n-type and a voltage is produced. this is the photo voltaic effect

63
Q

Mrs Lindsay’s equation

A

Vr = (Rr/Rt.)xVo

physics higher sqa (2 decks)

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