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external revision Flashcards

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Physics 101 flashcards AP® Physics flashcards
1
Q

horizontal and vertical components are _____ of eachother

A

independent

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2
Q

define the term normal force

A

the force acting along an imaginary line drawn perpendicular to the surface

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3
Q

describe uniform circular motion

A

the motion of an object travelling at a constant speed in a circle. Force acting on an object is perpendicular to the velocity of the object (velocity is tangential to the motion of the object)

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4
Q

define centripetal acceleration and force

A

the acceleration and the force experienced by any object moving in a circular path directed towards the centre of motion.

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5
Q

recall newton’s law of universal gravitation

A

the force of attraction between each pair of point particle is directly proportional to the product of their masses and inversely proportional to the square of the distance between them

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6
Q

define the term gravitational fields

A

is the region of space surrounding a body in which another body experiences a force of gravitational attraction

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7
Q

recall kepler’s law of planetary motion

A
  • First law of planetary motion states that all planets move about the Sun in elliptical orbits, having the Sun as one of their foci
  • Second law of planetary motion (law of areas) states that a radius vector joining any planet to the Sun sweeps out equal areas in equal lengths of time
  • Third law of planetary motion (law of periods) states that the square of the sidereal period of a planet is directly proportional the cube of its mean distance from the Sun T^2/r^3
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8
Q

define coulomb’s law

A
  • describes the force exerted by electrostatically charged objects on other electrostatically charged objects
  • that like electric charges repel and opposite electrical charges attract
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9
Q

define the terms electric fields, electric field strength and electrical potential energy

A
  • Electric field is a region of space near an electrically charged particle or object within which a force would be exerted on other electrically charged particles or objects
  • Electric field strength is the intensity of an electric field at a particular location (NC-1)
  • Electrical potential energy is the capacity of electric charge carriers to do work due to their position in an electric field (J)
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10
Q

define the term magnetic field

A

is a region of space where a magnetic force is experienced

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11
Q

explain the right hand palm rule

A

palm - force
fingers - field direction
thumb - current

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12
Q

explain the right hand grip rule

A

fingers - field/current direction
thumb - north pole (magnetic field direction/current)

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13
Q

define magnetic flux

A

a measurement of the total magnetic field that passes through a given area

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14
Q

define electromagnetic induction

A

the production of an electromotive force (EMF) or voltage across an electrical conductor due to its dynamic interaction with a magnetic field

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15
Q

define electromotive force

A

(EMF) is the difference in potential that tends to give rise to an electric current

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16
Q

define faraday’s law

A

states that when the magnetic flux linking a circuit changes, an electromotive force is induced in the circuit proportional to the rate of change of the flux linkage

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17
Q

define lenz’s law

A

states that the direction of an induced electric current is such that it produces a current whose magnetic field opposes the change in the circuit or the magnetic field that produces it

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18
Q

describe the process of inducing an EMF across a moving conductor in a magnetic field

A

change any of the variables in the formula eg. the field strength, the area, the angle or the number of turns

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19
Q

explain how transformers work in terms of Faraday’s Law and electromagnetic induction

A
  • work through mutual induction - the production of an EMF
  • transfers an alternating current from one circuit to another, usually with an increase or decrease in voltage
20
Q

define and explain electromagnetic radiation in terms of electric fields and magnetic fields.

A

refers to the waves of the electromagnetic field, propagating through space, carrying electromagnetic radiant energy (radio, microwave, x-ray)

21
Q

describe an example of natural phenomena that cannot be explained by Newtonian physics, such as the presence of muons in the atmosphere

A
  • the average life span of a muon is 2.2 microseconds and then decays into an electron and two neutrinos
  • This confirmed Einstein’s theory of relativity

○ To the observers, distance from mountaintop to sea level - 1910 (scientists’ frame of reference)
○ For the muon, the distance was 183m (muon’s frame of reference)
▪ Due to length contraction for objects travelling at relativistic speeds

○ Muon’s lifetime changed from 2.2 microseconds to 23 microseconds
▪ Due to time dilation for objects travelling at relativistic speeds`

22
Q

define the terms frame of reference and inertial frame of reference

A

is a non-accelerating frame of reference in which Newton’s laws of motion hold

23
Q

recall the two postulates of special relativity

A
  1. The laws of physics are the same in all inertial frames of reference
  2. The speed of light has a constant value for all observers, regardless of their motion or the motion of the source
24
Q

explain the concept of simultaneity

A

relation between two events assumed to be happening at the same time in a frame of reference
- Relativity of simultaneity states that events that are simultaneous in one frame of reference are not necessarily simultaneous in another frame of reference, even if both frames are inertial

e.g. if two school bells ring, and you are positioned directly between them, they will be heard simultaneously. However, if you are positioned closer to one of the bells, you will hear one before the other, meaning the event is not simultaneous

25
Q

explain the twin paradox

A
  • There are two twins, A and B. B goes on a spaceship (at a relativistic speed) to the moon, and returns years later

In the frame of reference of twin A, twin B has been moving very quickly, so will experience time more slowly (will measure less time). Therefore, twin B will be younger than twin A
In the frame of reference of twin B, twin A has been moving very quickly, so will experience time more slowly. Therefore twin A will be younger than twin B
- Who is correct?

Twin B is accelerating when he turns around to come back to Earth (therefore not an inertial frame of reference, and special relativity only applies for inertial frames of reference). Therefore Twin A’s statement is correct, and Twin B will be younger than Twin A

26
Q

recall the mass-energy equivalence relationship

A

relates change in mass to change in energy, given by ΔE = Δmc2

27
Q

explain why no object can travel at the speed of light in a vacuum

A
  • Objects with a mass cannot travel at the speed of light in a vacuum

As velocity approaches the speed of light, the momentum approaches infinity
The amount of energy/work required for each increment of velocity gets larger and larger, until the added effort produces no gain in speed

28
Q

explain the ladder paradox

A
  • Assume a ladder moves quickly towards a barn, with open doors at the front and back of the barn (at a relativistic speed). The ladder is longer than the length of the barn when both are at rest

From the barn’s perspective, the ladder experiences length contraction and can fit in the barn
From the ladder’s perspective, the barn experiences length contraction and the ladder can’t fit
- What happens?

The relativity of simultaneity needs to be considered. The two events are seeing the front of the ladder in the barn, and seeing the back of the ladder in the barn. These events are simultaneous for the barn, but not simultaneous for the ladder
Therefore, the ladder fits in the barn

29
Q

explain the flashlights on a train paradox

A
  • Man A is on a train travelling at a relativistic speed and Man B is standing on a platform. In the middle of the train is a lightbulb, and on the ends are light-activated doors

In the frame of reference of Man A, when the bulb switches on, the light travels at constant speed and takes the same time to travel to each door. Therefore, the doors will open simultaneously
In the frame of reference of Man B, when the bulb switches on, the left door is closer to the light than the right door as the train continues to move forward. The left door opens before the right door.
- Which frame of reference is more useful?

Both Man A and Man B are correct, it just depends on the frame of reference

30
Q

explain how Young’s double slit experiment provides evidence for the wave model of light

A

demonstrates the wave nature of light by allowing two coherent beams of light to overlap on a screen to form an interference pattern
- Monochromatic light diffracted into coherent circular waves and interacted to form constructive interference (antinodal - bright fringes of light) and destructive interference (nodal - dark fringes)

31
Q

describe light as an electromagnetic wave

A

produced by an oscillating electric charge that produces mutually perpendicular oscillating electric fields and magnetic fields

32
Q

explain the concept of black body radiation

A
  • A blackbody is an object that absorbs all radiation falling on it, at all wavelengths. It is a perfect absorber or emitter of radiation, and hollowed-out charcoal is commonly used as a black-body
  • Blackbody radiation is the radiation emitted by a black-body from the conversion of thermal energy, and which has a characteristic frequency distribution on temperature (wavelength = b/T)
33
Q

describe the concept of Photon

A

the smallest discrete packets of energy of electromagnetic waves

34
Q

describe the photoelectric effect in terms of the photon

A

the emission of electrons (or other free carriers) when light shines on a material. When UV is incident on a piece of metal, the metal becomes positively charged as electrons are ejected from the surface of the metal

35
Q

define threshold frequency

A

the minimum frequency of a photon that can eject an electron from a surface

36
Q

describe the rutherford’s model of the atom including it’s limitations

A
  • The atom is mostly empty space with a tiny, very dense postively charged nucleus surrounded by negatively charged electrons
  • The number of electrons = number of positive charges
  • Nearly 100% of the atom’s mass is contained in the nucleus
  • Limitations of Rutherford’s model include:

According to Maxwell’s electromagnetic equations, any electron revolving in a circular path should radiate electromagnetic energy. The electron would continuously lose energy and spiral in towards the nucleus, making the atom unstable and implode. The model did not consider this
The Rutherford model allowed electrons to have any energy, and therefore the light produced from them would be a continuous spectrum (where every wavelength of light is produced). This does not match the emission spectra observed, where only specific wavelengths are seen

37
Q

describe the bohr model of the atom and how it addresses the limitation of Rutherford’s model

A
  • Electrons in an atom exist in stationary states, they do not emit energy while orbiting
  • If the atom absorbs too much energy, the outermost electron will be removed. This is the ionisation energy
  • Angular momentum of a stationary electron is quantised therefore electrons must orbit at a fixed radii
38
Q

describe wave-particle duality of light by identifying evidence that supports the wave characteristics of light and evidence that supports the particle characteristics of light.

A
  • In general if light energy is interacting with other forms of light energy, then wave behaviour model is the best explanation
  • If light is interacting with matter, particle behaviour model is the best explanation
  • Mechanical waves are waves that require an elastic medium for the transfer of energy
    ▪ Not light as light can travel through a vacuum
39
Q

define the concept of an elementary particle and antiparticle

A

An elementary particle is a particle with no substructure, and thus not composed of other particles

▪ Lepton

▪ Quark

▪ Gauge bosons

▪ Higgs bosons
An antiparticle is a particle that has the same mass and opposite charge and/or spin as a corresponding particle. annihilate each other, giving off gamma rays

40
Q

recall the six types of quarks

A

up (2/3), down (-1/3), charm, strange, top, bottom

41
Q

define the terms hadron, baryon and meson

A
  • Hadrons are particles composed of quarks and gluons
  • Mesons are a subatomic particle composed of one quark and one antiquark, held together by the strong nuclear force.
  • Baryons are composite subatomic particles made up of three quarks or antiquarks (antibaryon) and held together by the strong nuclear force.
42
Q

recall the six types of leptons

A

the electron and electron neutrino, the muon and muon neutrino, and the tau and tau neutrino

43
Q

recall the four gauge bosons

A

gluons, photons, W boson, Z boson

44
Q

describe the strong nuclear, weak nuclear and electromagnetic forces in terms of the gauge bosons

A
  • Strong - quarks only, gluons mediated
  • Electromagnetic - photon
  • Weak - W and Z boson
45
Q

contrast the fundamental forces experienced by quarks and leptons.

A
  • Strong nuclear - quarks with nucleons
  • Electromagnetic - quarks and leptons with charge
  • Weak nuclear - all quarks and leptons
46
Q

define the concept of lepton number and baryon number

A

Leptons = 1
Anti-leptons = -1
Non leptons = 0

Baryon = 1/3 (number of leptons - number of antileptons)

Physics (8 decks)

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