Concepts

Question 1

What are the formulas to describe motion?

Answer 1

Speed = (change in position)/(change in time)
Acceleration = (change in velocity)/(change in time)
Momentum = (mass)x(velocity)

Question 2

What is conservation of momentum?

Answer 2

Momentum is conserved when there are no net forces acting on an object.

Question 3

What are Newton’s Three Theories of Motion?

Answer 3

1. An object’s velocity is constant unless acted upon by an outside force
2. The acceleration (a) of an object produced by a force is directly related to the magnitude of the force. a = FNET/m
3. Every action has an equal and opposite reaction.

Question 4

What is Newton’s Theory of Gravity?

Answer 4

Objects with mass have an attractive gravitational force between them. FG = GMm/R2

Question 5

What is energy? Kinetic vs. Potential energy

Answer 5

Energy is the ability to do work.
Kinetic energy is associated with an object’s motion, while potential energy is concerned with an object’s position relative to something that can exert a force on it.

Question 6

What is electric charge?

Answer 6

It’s another property of an object (like mass). According to Classical Mechanics, objects with opposite net charges will attract each other, and objects with the same net charge will repel each other.

Question 7

Explain the electric force between objects.

Answer 7

Coulomb’s theory to calculate the electric force between objects is FE = KqQ/R2

Question 8

How do you calculate electric force on an object?

Answer 8

FE = qE

Question 9

What is the Faraday Effect?

Answer 9

When an electrically charged object moves, it creates an electric current.

Question 10

What are Maxwell’s Four Equations that relate electric and magnetic fields?

Answer 10

1. Summarizes observations related to electric charge.
2. Magnetic field lines form closed loops. There are no isolated magnetic poles.
3. A changing (moving) magnetic field creates an electric field
4. A changing electric field produces a magnetic field

Question 11

Explain waves, and the equations involving wavespeed

Answer 11

Waves are patterns that exist in a substance. Light is wave-like, except it doesn’t need a substance to travel through. Maxwell discovered waves in electromagnetic fields.
Wavespeed = wavelength x frequency
v = (lambda)(nu)

Question 12

Explain greenhouse gases and the Earth’s atmosphere

Answer 12

The atmosphere helps regulate Earth's temperature. 
Greenhouse gases (CO2, methane) trap some of the radiation that comes from the Earth's surface.

Question 13

Explain the superposition of waves (Constructive vs. Destructive interference)

Answer 13

When waves are superposed, they can either travel in similar patterns (constructive interference) which doubles the wave’s amplitude, or opposite patterns (destructive interference) which flatlines the waves.

Question 14

Explain Young’s DSE

Answer 14

It proves that light is wave-like, because light defracts after travelling through the slits. Light is not a classical wave, because it doesn’t need to travel through a substance.

Question 15

Explain the subway experiment in regards to S. Relativity

Answer 15

Events can have different time frames when measured from different positions.
If Alice is on a subway and Bob is on the ground watching it pass, they will measure different times (t and t’) for the subway to pass a marker.
Bob find the subway to have length L = vt
Alice finds the subway to have length L’ = vt’
The lengths are related; L=L’/gamma

Question 16

Explain Intrinsic Energy

Answer 16

Intrinsic energy means objects have energy because they have mass.
Einstein showed this using Eo=mc2.
If an object is in motion but has no potential energy, then its total energy is E=Eo+(kinetic energy), E=(gamma)mc2

Question 17

Explain the moving light clock experiment

Answer 17

Alice is on a train with a light clock, and Bob is on the ground. When the clock ticks, Bob measures a greater time than Alice, because he sees it move further.

Question 18

Explain the Twin Paradox

Answer 18

Alice is in a rocket that circles a distant star and returns and Bob is on Earth. If they both time Alice’s trip, the time on Alice’s stopwatch will be less than Bob’s, because she has to accelerate around the star to turn around. She would also come back younger.

Question 19

What is the Principle of Equivalence?

Answer 19

It says that acceleration can mimic gravity. If Alice drops something in her space elevator, it will appear to fall, not because of gravity but because the floor rises to meet it.

Question 20

Explain gravity and space-time

Answer 20

Gravity is a consequence of space-time; space-time is a 4D coordinate system (x, y, z, t) made for identifying events. It bends around objects with mass.

Question 21

What are Einstein’s two main ideas about General Relativity?

Answer 21

1. Objects and light move on geodesics in space-time, which is the shortest path between two events in space-time.
2. Objects change the shape or curvature of space-time.

Question 22

Explain the bending of light in Alice’s elevator

Answer 22

If a beam of light enters Alice’s elevator while it’s accelerating, the light will appear to bend. It enters and exits the elevator at different points.

Question 23

What is gravitational lensing?

Answer 23

It’s when light is diverted along multiple pathways through dark matter, and images of a distant galaxy emitting light appear in different locations.

Question 24

Explain Mercury’s precession

Answer 24

Mercury’s ellipse around the Sun isn’t perfect; it’s affected by Venus and Earth’s gravitational pulls, as well as the curvature of space-time created by the Sun.

Question 25

Explain the Doppler Effect

Answer 25

A source emits waves toward the observer. If the source moves toward the observer, there will be a blue shift of waves and if it moves away, the waves will be red-shifted.

Question 26

What are gravitational waves and how are they created?

Answer 26

Accelerating objects with mass will produce gravitational waves in space-time that travel at c in empty space.

Question 27

Explain black holes

Answer 27

They're created when the fusion of nuclei in a star runs out. The star begins to collapse, the bending of space-time around it becomes infinitely sharp at a point called the singularity and objects/light inside the event horizon are directed toward this point

Question 28

The Big Bang theory claims

Answer 28

everything started from a blackhole's singularity

Question 29

What is blackbody radiation?

Answer 29

A blackbody emits and absorbs electromagnetic radiation in discrete or quantized amounts. It emits and absorbs radiation in portions represented by Planck's equation E=h(nu). ATOMS ARE NOT STABLE however they continuously emit light and energy

Question 30

Compare classical and quantum mechanics

Answer 30

Classical: on a larger scale, idealized Quantum: subatomic, only quantum entities instead of classical waves/particles

Question 31

What are photoelectrons?

Answer 31

Photoelectrons are electrons that have been kicked out of a photocell by light.

Question 32

Bright vs Dim light

Answer 32

1. Bright light has a greater amplitude, and will kick out more electrons 2. Dim light has a smaller amplitude and will take more time to kick out electrons

Question 33

What do observations of the Photoelectric effect reveal?

Answer 33

1. Frequency is important in creating photoelectrons; bright light that doesn't have the right frequency will not generate photoelectrons 2. If a photoelectron is created, it appears directly after light hits the metal, WITHOUT DELAY

Question 34

What's Einstein's Photoelectric Theory?

Answer 34

It proposes that 1. The energy associated with light comes in units of E=h(nu), which explains the first observation 2. The intensity of light depends on the number of E=h(nu) units of energy or photons present.

Question 35

How are the photons in the Photoelectric effect created?

Answer 35

By electrons jumping shells; when they go down a shell, a photon is released, and when it goes up a shell, a photon is absorbed

Question 36

Explain the Atomic Spectra (in general)

Answer 36

Every kind of atom has a unique atomic spectra; it can be revealed by sending some of its radiation through a prism onto a detector. A spectrum is a list of its frequencies or wavelengths. Each set of atoms will create a unique set of colours/quantum outcomes.

Question 37

Explain the integer n in regards to atomic spectra

Answer 37

Quantum states (ie. shells) that the atoms exist in are organized using the integer n, which corresponds to an energy level, En

Question 38

Explain Schrodinger's theory and equation

Answer 38

He said n has an associated energy En and a wave function, "psi"n, where n = 1, 2, 3... His equation allows you to calculate En and "psi"n for a given situation. "psi"p = "psi"s->s1->p + "psi"s->s2->p

Question 39

Explain the DSE with single particles

Answer 39

One particle fired through the slit results in one point on the detector, and enough will create an interference pattern. This shows that electrons are NOT classical particles, because they have wave-like properties, like light.

Question 40

What's a single particle's associated wave function?

Answer 40

"psi"p "psi"p = "psi"s->s1->p + "psi"s->s2->p

Question 41

Explain the superposition of states in the DSE

Answer 41

The two paths shown in a particle's wave function result in the superposition of states, which is where we add one quantum state to another. The MYSTERY associated with this is that when you know a superposition of an electron, you can't track its movement and vice versa.

Question 42

Explain indeterminacy and its associated equation

Answer 42

Indeterminacy means that it doesn't have a value, it can't be defined, like electrons don't have a specific position. There is an intrinsic indeterminacy associated with a point called x, and the momentum p toward it. ("delta"x)("delta"p) >/ h/4"pi", where "delta"x is the spread of particles.