Physics Exam Flashcards
Kinematics
the study of motion (how objects move)
Scalar
- only magnitude
- no direction
Vector (->)
- direction based
- need reference point
- grid
Distance (d)
total path travelled (NO DIRECTION) d1+d2+d3…
Position (-> d)
the distance and direction of
an object from a reference point.
Instantaneous Velocity
the limit of the average velocity as the elapsed time approaches zero
Displacement (∆d):
the change in position of an object in
a given direction.
units: (m)
∆d = d2 (final) – d1 (initial)
Total Displacement (->∆d):
the vector sum of individual
displacements.
units: (m)
∆d = ∆d1 + ∆d2 + ∆d3 + …
Speed (v):
is the distance divided by the travel time.
units: (m/s)
vav = d / ∆t
Velocity (-> v):
is the change in displacement or total displacement divided by the time interval for that
change.
Units: (m/s)
v = Δd / ∆t
Acceleration (-> a):
is the change in velocity divided by the time
interval for that change
units: (m/s^2)
a = Δv/Δt
= Δv final - Δv initial/ Δt
Acceleration due to gravity (g)
- the acceleration of an
object falling vertically towards the Earth’s surface. - g = 9.80 m/s2 [D]
- the greater
the distance from the Earth’s centre, the lower the
acceleration due to gravity
d-t → v-t
- take the rise over run from first two points of dt graph and whatever the number is is the velocity and can then be plotted in graph
area of vt graph
displacement
area of pt
nothing
net or resultant vector
(R)
the sum of all other vectors added tip to tail when adding vectors
Relative velocity
velocity of an object relative to a specific frame of reference
- most common frame of reference is the ground
Projectile motion
- an object in motion stays in motion
- Projectile motion is with a constant horizontal velocity combined with a constant vertical acceleration due to gravity
- necessary to break the problem into x and y components
Forces
- a push or pull in a specific direction that causes an object to change its motion
- a vector quantity
Dynamics
- causes of motion
- measurements in Newtons
Gravity (Fg)
action at a distance; does not need physical contact to work
Friction (Ff)
Opposes the motion
Applied (Fa)
Push or pull caused by object
Tension (Ft)
Pulling force
Normal (Fn)
Perpendicular to SURFACE
Net force
Sum of all forces acting on an object
Newtons first law
An object will remain at rest or continue to move at a constant velocity when net force of object = 0
Inertia
the property of matter that causes it to resist changes in motion
Rules of 1st Law
- a non zero net force WILL change the velocity of an object. The velocity can change in magnitude, direction or both
- A net force isnt required to maintain velocity
- External forces are required to change motion of object (push/pull)
- Internal forces have NO effect on the motion of an object
- When an object is at rest, it wants to stay at rest, if its in motion it stays in motion
Newton’s third law
For every action, there is a simultaneous reaction force that is equal in magnitude but opposite in direction
- negative sign means opposite direction
Fa on b = -Fb on a
Newton’s Second Law
- If the net force acting on an object is not zero, the object will accelerate in the direction of the net force
- the larger the mass, smaller acceleration
- smaller mass, larger acceleration
Fnet = ma
Drag force
opposing force
Mach # Less than 1
Subsonic
Mach # 1-5
Supersonic
Mach # More than 5
Hypersonic
Mach #
Ratio of speed of source to speed of sound
Transmission
- passing of wave energy from one medium to another at a boundary.
- When a wave moves from one medium to another, its frequency remains the same BUT its speed and wavelength change
Intensity of Sound
energy per unit area that passes a point each second.
units are J/m^2/s which is the same as w/m^2
Wave
A disturbance that transfers energy through a medium
Vibration
the cylical motion of an object about a rest position
Mechanical waves
waves that REQUIRE matter/ a medium to travel (e.g. water, sound)
Electromagnetic waves
Waves that cannot travel through some forms of matter, but also through a vacuum (e.g. space)
Crest
Highest point of amplitude
Area above rest position
Trough
Area below rest, max negative
Amplitude
Magnitude of the greatest displacement from the rest position in a crest or trough
Rest position
where the medium’s equilibrium or undisturbed position would be
Wavelength (λ)
The distance of one full cycle of a wave
The distance between a crest or trough
Frequency (f)
the # of cycles (N) that occur over a time (s)
units: Hz
F= N/t
Period (T)
the time (s) for a vibrating particle to complete one cycle
T= t/N
Absorption
process where wave’s energy is quickly dissipated by being transformed into other forms of energy (e.g. sound causes vibration)
Reflection
a wave reaches boundary and has energy reverted towards the initial wave propagation
Speed of sound in air
dependant on temperature
v = 332 m/s + (0.59 m/s) (T)
where T = temperature
Kirchoff’s Current Law
Series: current is the same
Parallel: current adds up
Kirchoff’s Voltage Rule
Series: voltage adds up
Parallel: same
Faraday’s Law of Induction
a magnetic field that is moving or changing intensity near a conductor causes or induces electron flow or current in said conductor
Generator
made up of permanent magnets and coils of wire, designed to produce a continuous flow of electric current
Lenz’s Law
if there is change in magnetic field, a current will be induced to respond to the change
Step up transformer
Np < Ns
Step down transformer
Np > Ns
The more loops…
the greater the field strength
Solenoid
coiled conductor used to create electromagnets (any device that produces magnetic field as a result of electric current)
Factors that effect Solenoid
- current in the coil: greater the current, greater field strength
- # of coil turns: more coils, greater field strength
- type of material: more ferromagnetic, greater f.s
- size of coil: smaller in diameter, greater in f.s
Magnetic field
region of space around a magnet that causes a magnetic force on magnetic objects
Magnetic field lines
Point from north to south on the outside, but south to north on the inside
NEVER cross
Closer together when field is stronger
Which magnets attract?
opposites (north to south)
Which magnets repel?
like objects (north to north / south to south)
Oersted’s Principle
Whenever charge moves through a straight conductor, a circular magnetic field is created around the conductor
Right hand rule #1
FOR SINGLE WIRE
Thumb = Current
Fingers = North
Right hand rule #2
FOR SOLENOIDS
Thumb = North
Fingers = Current
Conventional flow
Positive terminal to negative
Electron flow
Negative terminal to positive
Charge (Q)
- negative particle that moves along conductors in a circuit
- unit: coulombs (C)
Current (I)
- unit: Ampere (A)
- total amount of charge moving past a point in conductor, divided by time taken
I = Q/Δ t
Potential Difference (Or Voltage) (V)
- unit: voltage/ volts (V)
- the electric potential energy for each coulomb of charge in a circuit
- voltage measured by 2 points in circuit
Resistence (R)
- unit: ohms (Ω)
- property that hinders electron flow
- converts energy to other forms
- greater the resistence, more energy
Power (P)
- units: Watts (W)
- rate at which work occurs
- result of energy dissipation in circuits overtime
Energy (E)
- units: Joules (J)
- electric and magnetic field formed in the space surrounding wires containing flowing charges
E = PΔ t or E= V
Binding energy
the energy used to hold the nucleus together
Nuclear Fusion
when nuclei of two or more atoms fuse and form a larger one
Nuclear Fission
Decomposition of large, unstable nuclei in smaller stable ones
Transmutation
process in which the atomic number of a nucleus changes, which converts to a different element
Alpha Decay
- helim nuclei
- ᴬX -> Yᵃ-⁴ + ⁴₂ He
ᶻ ᶻ-² - Penetration: 5cm in air, doesnt penetrate skin
- Ionizing ability: high
- Risks: Ingestion
Beta Positive Decay
ᴬX -> ᴬY + ⁰e
z z+1 -¹
Beta Negative Decay
ᴬX -> ᴬY + ⁰e
z z-1 +¹
Electron Capture
ᴬX + ⁰e -> ᴬY
z -¹ z-1
Gamma Decay
ᴬX * -> ᴬX + ⁰₀ γ
z z
- Penetration: 2km in air, can go through entire body
- Ionizing ability: do not ionize atoms directly but causes atom to emit particles that CAUSE ionization
- Risks: HIGH (to reduce use proper shielding like lead, concrete or soil)
Beta Decay Risks
- Pentration: 30-50cm in air, 1cm into skin
- Ionizing ability: Moderate
- Risks: Greatest due to ingestion & naturally penetrates skin
Isotope
Element that have same number of protons but diff number of neutrons
Radiation
the emission of energy in the form of waves of fast moving particles. this energy can be transferred to matter
Alternating Current (AC)
- waves
- Current that continuously changes direction
Direct Current (DC)
- linear
- Current that flows in a single direction
Ionizing Radiation
consists of waves or particles that carry enough energy to remove electrons
Background Radiation
ionizing radiation emitted from natural sources (minerals, rocks, tobacco, cosmic rays, brick, medical imaging)
Nuclear Radiation
ionizing radiation emitted from nucleus of an atom. An unstable nucleus spontaneously sends out particles and electromagnetic radiation, transforming an atom of one type into another
Latent Heat
the thermal energy needed for a phase change
latent = hidden
Latent heat of Fusion
Melting
solid to liquid
Latent heat of Vapourization
Boiling
liquid to gas
Thermal Expansion
substance when warmed
Thermal conduction
Substance when cooled
Specific Heat Capacity (c)
the amount of energy, in joules, to increase the temp of 1kg by 1 celsius
Quantity of heat (Q)
the amount of thermal energy transferred from one object to another. Takes into account mass, heat capacity and change in temp
Q= mcΔT
Principal of Thermal Energy Exchange
when thermal energy is transferred from warmer object to a cooler one, the amount of energy is released by the warmer one is = absorbed by the cooler object
Q₁ = -Q₂
Heat
the transfer of thermal energy from a substance with a higher temperature to a substance with a lower temp. (warmer to colder)
Thermal Conduction
PHYSICAL transfer of energy
Thermal Convection
Transfer of thermal energy through a FLUID
- occurs when colder, denser fluid falls and pushes up the warmer, less dense fluid
- convection current is a current that occurs when a fluid is continuously heated
Thermal Radiation
movement of thermal energy as electromagnetic waves being emitted from sources such as lamps, flames and sun
Conductors
Allow thermal energy to pass through easy (metals and metalloids)
Insulators
Dont allow thermal energy to pass (wood, plastic, still air)
Temperature
measure of the average kinetic energy of the particles in a substance
Thermal Energy
- energy possessed by randomly moving atoms and molecules
- potential and kinetic
Mechanical Energy
- potential & kinetic
- possessed by objects affected by gravity and friction forces
- sum of Ek and Eg
Potential Energy
- a form of energy an object possesses because of its position in relation to forces in its environment
- ability of object to do work
Eg= mgh
Radiant (Light) Energy
- potential & kinetic
Electrical (Static) Energy
- potential
- energy possessed by accumulated static charges
Electrical (Current) Energy
- potential & kinetic
- energy posessed by flowing charges
Sound Energy
- potential & kinetic
- energy possessed by large groups of oscillating atoms and molecules
Elastic/Spring Energy
- potential
- energy possessed by materials that are stretched, compressed, or twisted and tend to return to original shape
Nuclear Energy
- potential
- energy possessed by protons and neutrons in atomic nuclei
Chemical Energy
- potential
- energy associated with bonds in molecules
Energy Transformation
the change or conversion of one type of energy into another
Gravitational Energy
energy possessed by an object due to its position relative above a reference level
Energy
The capacity to do WORK
- all moving objects possess kinetic energy
Ek = 1/2 mv²
Work
Applying a force on an object that displaces the object in the direction of the force
W= FΔdcosθ
Reference Level
a designated level to which objects may fall; considered to have a Eg energy value of 0
The Motor Principle
A current carrying conductor that cuts across external magnetic field lines experiences a force perpendicular to both the magnetic field and the direction of electric current
Half-life
Time required for one half of the atoms in radioisotope to decay
