Studied by 4 peopleOrigin
The location at which original motion begins.
Position
The location of an object (requires a distance from the origin).
Distance
The length of the path travelled by an object.
Displacement
The object’s change in position from its origin.
Scalar (Scalar Quantity)
A quantity that represents magnitude only (i.e. only amount) (e.g. time, mass, length, etc).
Vector (Vector Quantity)
A quantity that has a magnitude and direction (e.g. position, displacement, force, etc). Vectors are represented symbolically by a small arrow over the variable and graphically by arrows of varying lengths. Directions can be described in several ways: compass directions, left/right or up/down, a number line with positive and negative values, etc.
Time Instant
A single clock reading. Not a length of time.
Time Interval
A duration or period of time. It is the time separating two separate instances (t[final] - t[initial] = t[interval]).
Rate
How much a quantity changes in a period of time. This rate is quantity divided by time:
v = d/t
a = v/t
current = charge moving past a point/time (C/s)
Uniform Velocity
Objects travelling that are not changing their speed or direction (linear on a d-t graph, zero slope on a v-t graph, zero value on an a-t graph).
Average Velocity
Calculated by taking two points from the beginning and end of the time interval you are looking for, connecting them, and finding the slope (on a d-t graph).
Instantaneous Velocity
Calculated by drawing a tangent line to the point your are looking for, then finding the slope of that line (on a d-t graph).
If the line on the d-t graph is not curved, the instantaneous velocity along any of those points is just the slope of the line.
Force
A push or pull.
Gravity
Fg=mg
Infinite range (with mass).
Wins at a large scale.
An attraction between two masses, requires mass to exist.
Strong Nuclear
Wins at the atomic scale.
Small range (nucleus).
Attraction between protons and neutrons, responsible for the stability of matter.
Weak Nuclear
Loses at the atomic scale.
Very small range (nucleus), smaller than strong nuclear.
Nuclear energy.
Radioactive decay.
One atom degrades to another.
Electromagnetic
Wins at a molecular scale.
Infinite range (with charge).
Occurs between any two charged particles.
Can be attractive or repulsive.
Binds together the atoms and molecules that make up everything.
Newton’s First Law
An object in motion remains in motion unless acted upon by an outside unbalanced net force. Also called the Law of Inertia.
Net Force
The vector sum of all forces acting on a body.
Inertia
The ability of an object to resist changes it its state of motion.
Free-Body Diagram (FBD)
A diagram that represents an object and all the forces acting on it.
Non-Contact Force
A force between two objects that arises when the objects are not in contact with each other.
Contact Force
A force that arises when two objects are in contact.
Friction
A force opposing the relative motion of two objects that are in contact.
Normal Force
A force that acts perpendicular (90°) to the surface of contact.
Newton (N)
The force required to accelerate a 1kg mass at 1m/s/s.
Tension
A force transmitted through a rope, string, or wire.
Applied Force
A force applied to an object by another object.
Static Friction
A force that keeps an object at rest when an insufficient force is applied.
The opposing frictional force will continue to increase until the maximum is reached (F[static friction] = µF[normal] is used to calculate the maximum, µ is the coefficient of friction and is a percentage of frictional to normal force with no units, so static friction depends on normal force, as well as the materials of the objects).
Acts to oppose the beginning of motion, and is greater than kinetic friction.
Kinetic Friction
A force that acts between moving surfaces; opposes motion.
The opposing frictional force cannot cause motion, even if it is greater than the force applied. (F[kinetic friction] = µF[normal] is used to calculate the frictional force, µ is the coefficient of friction and is a percentage of frictional to normal force with no units, so kinetic friction depends on normal force, as well as the materials of the objects).
Acts against two objects sliding across each other, and is less than static friction.
Newton’s Second Law
F = ma
Newton’s Third Law
For every action force, there exists a reaction force that is equal in magnitude, but opposite in direction.
Every action has an equal and opposite reaction (e.g. the force of gravity is frequently opposed by normal force).
Terminal Velocity
When a falling object’s air resistance force is equal to its gravitational force. It falls at a constant velocity, its net force and acceleration are zero.
Air resistance depends on an object’s surface area and shape. It increases as the falling object’s speed increases.
Not all objects have the same terminal velocity! Just the same g = 9.81 m/s/s that can be used to calculate the force of gravity.
When comparing two masses, to figure out which one will reach terminal first, you must first determine which one experiences a greater gravitational force, and which one experiences a greater resistance force.
What causes motion?
A net force acting on an object.
What quantity does not change as a wave is partially transmitted or reflected?
Frequency; it is constant because it is determined at the creation of the wave by the source.
What quantity always decreases in size as a wave is partially transmitted or reflected?
Amplitude; the energy from the initial wave splits and is absorbed, causing the amplitude to decrease.
Wave
Energy propagating through substance or medium.
Medium
A material that moves energy from one location to another.
Pulse
A single wave being transmitted.
Periodic Wave
A pulse occurring at regular intervals.
Cycle
One complete vibration, pulse, or disturbance.
Frequency
The number of cycles that occur in a specific period of time.
Period
The amount of time needed for one complete cycle or wave to take place.
Amplitude
The maximum displacement a wave moves from its equilibrium position; its energy.
Standing Wave
The resultant of the interference between two waves with the same wavelength, frequency, and amplitude travelling in opposite directions through the same medium.
Node
The point that remains at rest when positive and negative pulses of equal amplitude and length travel in opposite directions and interfere; perfect destructive interference.
Antinode
Occur midway between the nodes, and are areas where double crests and double troughs occur; constructive interference/super crests and troughs.
Attenuation
A reduction in the energy of a travelling wave as it bounces off/moves through things.
Constructive Interference
Occurs when the resultant displacement is greater than the displacement that would be created by either wave.
Destructive Interference
Occurs when the resultant displacement is smaller than the displacement caused by one wave.
Super Crest/Super Trough
Areas of perfect doubling/constructive interference (crest is positive amplitude and trough is negative).
What are the 3 types of waves?
Mechanical Waves (medium needed, i.e. sound)
Electromagnetic Waves (medium, or absence of medium, i.e. light)
Gravitational Waves (very large masses produce waves that travel at the speed of light)
What are the 3 types of mechanical waves?
Transverse Waves: Amplitude is perpendicular to propagation. The crest is the highest point above the rest line and the trough is the lowest point below the rest line. The amplitude is the distance from the rest line to the crest or trough, and the wavelength is one complete crest and trough. Examples: a pendulum and a guitar string.
Longitudinal Waves: Amplitude is parallel to propagation. The compression zone is where the particles are close together, and the rarefaction zone is when the particles are spread apart. The amplitude is the amount by which the particles have been compressed or spread apart, and the wavelength is once complete compression and rarefaction. Examples: A coil spring or a sound wave.
Tortional Waves: Amplitude is around the axis of propagation. Examples: A wind-up toy and a tire swing.
How much of a wavelength is the distance between 2 nodes?
Half of a wavelength.
What causes a node? What causes an antinode?
A node occurs during perfect destructive interference: it is a point that has exactly the same positive and negative amplitude.
Antinodes are doubling amplitude points, either positive or negative, and occur halfway between the nodes.
How does v=d/t become v=λf?
v is the same quantity (speed) measured in m/s
d (distance) is replaced by λ (wavelength) measured in m
t (time) is replaced by T (period) measured in s
the equation is now v=λ/T, but since frequency (f, measured in hz) and period are reciprocals, T can be replaced with 1/f, making it v=λf
The Electromagnetic Spectrum
The far left of the spectrum has a longer wavelength and a lower frequency.
The far right of the spectrum has a shorter wavelength and a higher frequency.
Energy increases to the right.
From left to right: radio waves, micro waves, infrared, visible light, ultraviolet, x rays, gamma rays.
The visible light spectrum occurs between 400 to 700 nanometres, with respect to ROYGBV (i.e. red has a longer wavelength than violet).
True or False: A wave moves the medium it travels through.
False: A wave moves through a medium, but it does not move the medium.
A wave’s energy is transferred and moves through the medium, but after the wave has passed, the medium returns to its original state.
How does sound move?
Sound is a longitudinal wave made up of compressions and rarefactions. These waves are created by vibrating objects. Sound waves can only be transmitted through a medium; sound cannot exist in a vacuum.
How is the speed of sound different in solids, liquids, and gases? How does the speed of sound relate to the speed of light? How does the speed of sound in air change with temperature?
Sound moves fastest in solids, slower in liquids, and slowest in gases.
The speed of light is a million times grater than the speed of sound in air.
The speed of sound increases as temperature increases.
What causes beats?
When two sound waves with different frequencies interfere with each other. During the interference, there are areas of doubling (constructive) and cancelling (destructive) which is what creates the pulsing sound.
How does beat frequency relate to the tuning of musical instruments?
Example: A guitar player sounds an out-of-tune string along a tone from a source known to have the correct frequency. The guitarist adjusts the tension in the string until the beats vanish, ensuring that the string is vibrating at the correct frequency.
What is an example that demonstrates how sound carries energy?
When bombs are detonated, they release shock waves/sound waves that carry large amounts of energy which can break windows and causes damage, and would be very loud.
True or False: Higher frequency waves require more energy to create.
True (e.g. FM radio requires more energy, but it has a higher frequency and therefore more definition than AM radio).
What is Mach? What are the classifications of Mach? What happens when an object exceeds Mach?
Mach is the speed of sound. The value of Mach changes depending on the temperature (and other factors), it is not constant all the time. Mach is also a physical air barrier for things that move very quickly like airplanes, which can be restricting.
Before Mach 1, there is a build up of compression zones in front of the plane as it moves. When the plane moves faster than Mach 1, it breaks through those compressions, creating a sonic boom.
Anything before Mach 1 is subsonic (slower than the speed of sound), Mach 1 is sonic (equal to the speed of sound), Mach 1.000…1 to Mach 4.999…. is supersonic (faster than the speed of sound), and Mach 5+ is hypersonic (even more faster than the speed of sound).
What are the types of seismic waves?
Body Waves travel through the inner layers of Earth:
P-Waves: The ground compresses and expands parallel to travel direction and can move through solids, liquids, and gases.
S-Waves: Move the ground perpendicular to travel direction. Can travel through solids only.
Surface Waves travel along Earth’s surface:
Rayleigh: The ground moves up and down.
Love: The ground moves side to side.
Attenuation and Sound Waves
Higher frequency sound waves have more attenuation, meaning they lose amplitude faster than lower frequencies. This means that a lower frequency would sound louder at a certain point from the origin in relation to a higher frequency sound from the same origin (piano keys).
Audible Frequency Range
Humans can hear from 20Hz to 20KHz (20,000Hz). Frequencies below human hearing are called infrasound, and frequencies above human hearing are called ultrasound.
Resonant Frequency Definition
The frequency at which a standing wave exists.
Echolocation
Animals project sound and listen to the reflection it makes when it hits the different objects of the environment. These reflections allow the animal to get information regarding each object’s size, shape, distance, texture, etc.
What is the difference between weight and mass?
Weight is the force that gravity pulls on an object downwards (Fg=mg) and is measured in newtons (N). This means it changed depending on which planet you’re on.
Mass is measured in kilograms (kg) and stays constant anywhere (i.e. another planet or in space).
Definition of a field (general), an electric field, and a gravitational field.
A field is an area under the effect of a force and involved non-contact forces.
An electric field is the region around a charge where another charge experiences a force.
A gravitational field is a region around a mass where another mass experiences a force.
Positive Test Charge
A positive charge so small that the force it exerts does not significantly alter the distribution of the other charges (the ones that cause the field being measured).
Point Charge
An idealized charged particle with no real size or spatial extent.
Electric Field Lines/Lines of Force
The lines representing the direction of an electric field.
Coulomb (C)
The SI unit for charge (q).
Where does the value for the electric constant come from (k=9x10^9 Nm^2/C^2)
Two identically sized spheres separated by a distance of 1m and each have a charge of 1C would experience a force of 9x10^9 N. This can be determined using the formula Fe=(q1xq2xk)/(r^2).
How is the Law of Magnetic Poles similar to the way in which electric charges act?
Like poles repel each other and unlike poles attract each other. This is like how like charges repel and unlike charges attract.
Where are electric, magnetic, and gravitational fields the strongest?
Electric: At the charges.
Magnetic: At the poles.
Gravitational: At the mass.
What happens when a bar magnet is broken in two?
The bar magnet becomes two smaller magnets. Each broken piece still has an opposite pole because you can’t have a magnet with only one pole.
How does a compass work?
The magnetic pole in the north on Earth acts like the south side of a bar magnet. The north side of a compass is attracted to this, making the compass point to the geographical north pole.
What is a ferromagnetic material? Name a metal that is ferromagnetic and a metal that isn’t.
A ferromagnetic material is made up of domains that act like tiny magnets inside of it. Aligned domains create magnetism and unsorted means so magnetism.
Iron is ferromagnetic and tin is not.
What is the relationship between the Earth’s magnetic field and the sun? What causes the Earth’s magnetic field?
The sun’s energy interferes with the Earth’s magnetic field (stretches it). The Earth’s magnetic field protects us from the sun’s energy.
The Earth’s magnetic field is caused by the rotation of its core. It is not constant throughout its entire surface.
What proof do we have that the Earth’s magnetic field switches?
Convection cycles cause the tectonic plates to move, creating areas where the magma from inside Earth comes up to the surface.
While this is still liquid, the crystals align themselves with the Earth’s magnetic field, then the rock solidifies.
Since the crystals don’t move after they’re solid, we know the switch happens because the older rocks have different orientations than the newer ones, indicating that the crystals would have aligned when the poles were opposite.
What are some similarities between each type of field?
M + G = Earth has both.
M + E = Diagrams are similar, attractive or repulsive, N/S acts similar to +/-.
E + G = Similar equations, negative charge and gravitational have similar diagrams, needs mass/charge to exist.
All = Inverse square law (decreasing the distance increases the force), area under the affect of a force, non-contact forces.
How was the Millikan experiment conducted? How did he come up with his formula?
Millikan used batteries to charge two parallel plates. The top one was positive and the bottom one was negative. By adjusting the voltage he was able to change the electric field strength (E).
He sprayed a mist of oil droplets between the plates (negatively charged, because they gained electrons from friction). The mass (m) of the oil droplets was determined based on the volume and density.
Because the oil droplets were negatively charged and the positive plate was on the top, the electric and gravitational force worked opposite each other. When they were equal, the oil droplet would be suspended between the plates. Since this experiment was done on Earth, the value of g was 9.81N/kg.
Using Fg=mg and Fe=Eq, since Fg=Fe, mg=Eq, meaning q=mg/E where m is the mass of the oil droplet determined by the volume and density, g is 9.81N/kg because of the Earth, and E is known from adjusting the voltage on the batteries.
The charge values looked like (not actually) 56, 77, 35, 35, 70 … therefore, Millikan was able to determine the charge of an electron by finding the lowest common multiple of his results.
How can the number of electrons on an object be determined?
By dividing the charge of the object by the elementary charge.
What two factors determine the amount of air resistance an object experiences when falling?
Its surface area and velocity. More surface area/higher velocity means more air resistance experienced.
What is the acceleration of an object falling at its terminal velocity?
Zero
How could you determine which of two masses would reach its terminal velocity faster, and which one would have a larger terminal velocity?
If two masses have the same Fg, determine which one experiences a higher Ff. The higher Ff will reach its terminal velocity faster, and the lower Ff would have a greater terminal velocity because it would accelerate for longer.
If two masses have the same Ff, determine which one has a larger Fg. The lower Fg will reach its terminal velocity faster, and the higher Fg would have a greater terminal velocity because it would accelerate for longer.
When the force of friction is greater than the applied force, what happens to that object?
Nothing, it does not accelerate.
Which is typically greater, kinetic or static friction?
Static Friction
True or False: The static friction acting on an object at a specific time instant is calculated using Ff=μFN.
False: Ff=μFN calculates the maximum static friction before the object starts to move. The static friction acting at a specific time instant is opposite and equal to the force applied.
What is something unique about each type of field?
Gravitational fields are only attractive.
Earth does not have a prominent electric field.
A magnetic monopole does not exist: there will always be an opposing south to north and north to south.
Note 
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