Physics Flashcards
Vector
numbers that have direction and magnitude
Ex/ displacement, velocity, acceleration, force, weight
Scaler
numbers that have magnitude
Ex/ distance, speed, energy, pressure, mass, work
Dot product
the product of multiplying 2 vectors and the cosine of the angle between them to produce a scaler
A·B = |A| |B| cos 𝜃
Cross product
the product of multiplying 2 vectors and the sin of the angle between them to produce another vector
A x B = |A| |B| sin 𝜃
Velocity
Instantaneous speed of an object is equal to the magnitude of the objects instantaneous velocity (v) vector
v = Δx/Δt
Gravitational force
all objects exert gravitational forces on each other
Fg = Gm1m2 / r²
Newton’s first law
an object at rest, or in motion at constant velocity, will remain so until a force acts on it
Newton’s second law
F(net) = ma
Newton’s third law
- every force exerted by object A on object B, will result in a force by object B on object A
- F = -F
- For every reaction, there is an equal and opposite reaction
Kinematics equations
v = v₀ + at x = v₀t + 1/2at² —> x = v₀t + at² / 2 v² = v₀² + 2aΔx
Terminal velocity
When the drag force equals the magnitude of the weight of an object (object is falling at constant velocity). The force of gravity and air resistance are equal
Projectile motion
Force and acceleration in the vertical direction only. Distance can only be found with the horizontal components of the force
Incline planes
Fg (parallel) = mg sin 𝜃
Fg (perpendicular) = mg cos 𝜃
Normal force
equal in magnitude to the perpendicular component of gravity
Centripetal force
Fc = mv^2 / r
Centripetal acceleration
Ac = v^2 / r
Torque
Application of a force at some distance from the fulcrum
𝞃 = F x r = F x r (sin𝜃)
- 𝜃 is the angle between the lever arm and force vectors
Kinetic energy
KE = 1/2 mv²
Gravitational potential energy
U = mgh
Elastic potential energy
U = 1/2 kx²
When k is not given, F = |kx| —> k = F/x
Total mechanical energy
E = U + K
If there is an increase in 1, there is a decrease in the other
Conservative forces
Forces, like gravitational and electrostatic, that do not disrupt the flow of energy
Nonconservative forces
Forces like friction, air resistance, viscosity, and convection that do disrupt the flow
Work
Transfer of energy from one system to another
W = Fd = Fd x cosϴ
F = W / d —> F = KE / d
Isobaric process
When pressure of the system is constant and volume changes. This does not effect the 1st law
W = P∆V ( J = N/m² x m³)
Power
The rate at which energy is transferred. Unites in Watt (W) or J/s
P = W/t
P = ∆E/t (energy/time)
P = KE/t
Work-energy theorem
W = ∆KE = KEf - KEi
Mechanical advantage
MA = (force exerted on object by machine) / (force exerted on machine)
Efficiency
Efficiency = (load x load distance) / (effort x effort distance)
- Load is the weight and effort is the force
0th law of thermodynamics
If object A is in thermal equilibrium with object B, and object B is in thermal equilibrium with object C, then object A and object C are in thermal equilibrium. No net heat will flow between these objects
Heat
Transfer of thermal energy from a object with higher temp to one with lower
Thermal equillibrium
When no net heat flows between objects
Absolute zero
The lowest temperature possible where no heat is produced from the movement of particles. A substance at absolute zero displays no kinetic energy
Fahrenheit, Celsius, and Kelvin conversion
F = 9/5 C + 32 K = C + 273
Linear thermal expansion
∆L = ⱭL∆T
Volumetric thermal expansion
∆V = βV∆T
Isolated system
No exchange of energy or matter with the surroundings
Closed system
Exchange of energy, but not matter
Open system
Exchange of energy and matter
Calorie to joule conversion
1 Cal = 1000 cal (1 kcal) = 4184 J
Conduction
Direct transfer of energy through molecular collisions
Convection
Transfer of heat by the physical motion of fluid over a material. Only liquids and gasses exhibit this
Radiation
Transfer of energy through electromagnetic waves. This can be transferred in a vacuum
Specific heat
Relationship between adding/removing heat energy to a system and how much the temperature changes based on how much energy is added or removed.
q = mc∆T
Specific heat of water
1 cal/g·℃ or 4.184 J/g·K
Specific heat during a phase change
q = mL where L is the heat of fusion or vaporization
Heat of fusion
Heat of transformation at the melting point
Heat of vaporization
Heat of transformation at the boiling point
Isothermal process
When the system’s temperature is held constant so ∆U = 0 and Q = W
Adiabatic process
When there is no heat exchange between the system and surroundings so Q = 0 and ∆U = -W
Isovolumetric process
When there is no change in volume and no work is done in the process so W = 0 and ∆U = Q
Entropy
Measure of spontaneous dispersal of energy at a specific temp
∆S = Q (rev) / T
1st law of thermodynamics
Conservation of energy: Energy is not created or destroyed, just transferred from one form to another. Any change in the total energy of the system is due to work or heat
∆U = q - W or ∆U = q + W (if energy is being transferred out of the system)
2nd law of thermodynamics
Entropy always increases over time
∆S universe = ∆S system + ∆S surroundings > 0
3rd law of thermodynamics
Absolute zero temperature is unattainable
Density
ρ = m / V
Units: kg/m³ or g/mL —> g/cm³
Density of water
1 g/cm³ —> 1000 kg/m³
Specific gravity
The density of a substance compared to the density of water. Finding the difference in densities of a substance and water gives you the ability to find the density of the other solutes (excluding the substance and water)
SG = ρ / 1 g/cm³ or 1 g/mL
Pressure (fluids)
P = F/A
1 Pa = 1 N/m²
Pascal to atmosphere conversion
1.013 x 10⁵ Pa = 100 kPa = 760 mmHg = 760 torr = 1 atm
Absolute pressure
Also known as hydrostatic pressure
P = Po + ρgz
z = depth
Po = 10⁵ Pa
Gauge pressure
Pressure in a closed space above atmospheric pressure
Pgauge = P - Patm = (Po + ρgz) - Patm
Pascal’s prinicple
In a incompressible fluid, a change in pressure will be transmitted to each portion of the fluid and to the walls of the vessel
Archimede’s principle
When a object is wholly or partially immersed in a fluid, it will be buoyed upward by a force equal to the weight of the fluid that is displaced
Fbuoy = ρ(fluid) x V(fluid displaced) x g = ρ(fluid) x V(submerged) x g
Buyount force
Exerted by the mass of a fluid that is displaced (corresponds to the volume of fluid displaced). It always directed upward
Fbuoy = mg = ρVg
% of an object submerged
(ρ(object) / ρ(fluid)) x 100
Surface tension
Causes liquids to form a strong layer at the surface due to the increased intermolecular attraction
Cohesion
Attractive force that a molecule of liquid feels towards molecules of the same liquid. It leads to a net upward force
Adhesion
Attractive force that a molecule of liquid feels towards molecules of an other substance
Poiseuille’s Law
Q = 𝛑r⁴ΔP / 8𝛈L
*Assume laminar flow. In laminar flow, the center of the “pipe” moves fastest while the “edges” have no velocity due to the no-slip boundary
Continuity equation
Q = A₁v₁ = A₂v₂
Volume flow rate = Q = A1v1
Bernoulli’s equation
More energy dedicated to fluid movement means less energy dedicated to static fluid pressure
P₁ + 1/2ρv₁² + ρgh₁ = P₂ + 1/2ρv₂² + ρgh₂
Dynamic pressure
1/2ρv²
Static pressure
P + ρgh
Venturi effect
In a dumbbell shaped tube, point A has the larger radius and B is smaller. Going from A to B, the area decreases, but v increases. So as a fluid is flowing through, the dynamic pressure increases and the static pressure decreases. If a column of fluid is sticking up at A and B, the absolute pressure in B will be lower than A
Fainting
Occurs after there is insufficient blood flow to the brain. According to the equation P=pgz, decreases in height (or increase in depth) —> increase in pressure. So when blood flow is insufficient, you faint in order to decrease the height your brain is at so there can be an increase in pressure (more blood flow to brain)
Faraday’s constant
96,485 C/mol or 10⁵ C/mol
Coulomb’s law
Describes the electrostatic force between 2 charges
Fc = kq₁q₂ / r²
Test charge
q, the force place in the field
Source charge
Q, the force exerted by the field
Electric field lines
Drawn away from positive sources are towards negative sources. If the magnitude of the charge increases or decreases, the density (number of lines) of the lines increase or decreases
Electrical potential energy
A form of potential energy that is dependent on the relative position of a charge with respect to another charge
U = kQq / r²
U = qEd or U = qV
U = 1/2 CV²
Electric potential
The ratio of a charge’s electric potential energy to the magnitude of the charge itself
V = U/q or U = ΔVq
V is the electrical potential measured in Volts = 1 J/C
Dipole moment
p, the product of charge and separation distance. It is a vector that points from the (+) to (-) charge along d
p = qd
Diamagnetic materials
made up of unpaired electrons that have no net magnetic field. Ex/ wood, plastic
Paramagnetic materials
become weakly magnetized in the presence of a magnetic field. Ex/ Al, Au, Cu
Ferromagnetic materials
strongly magnetized in the presence of a magnetic field. Ex/ Fe, Ni, Co
Current
Amount of charge passing through a conductor per unit time
I = Q/Δt
1 A = 1 C/s
Potential difference
It is the voltage or the difference in potentials required for a current to flow
Electromotive force (emf)
the “pressure” or “force” that causes a current to move when there is a potential difference
Galvanic (voltaic) cell
Electrochemical cell that contains spontaneous oxidation-reduction reactions that generate emf as a result of the differences in reduction potentials of 2 electrodes and a salt bridge to prevent charge buildup
Junction rule
the sum of currents flowing into a point (or junction) must equal the sum of the currents flowing away from that point
Loop rule
in a closed circuit, the sum of the voltage that is used will always equal the sum of the voltage that is lost (dropped)
Resistance
the opposition of flow of charge
R = ρL / A
Ohm’s law
V = IR measured in Ω. Voltage and current are directly proportional when R is constant
Power
When energy is produced by a flow of electrons, electrical potential energy is converted to kinetic energy driven by the emf
P = W/t or P = ΔE/t
P = IV —> P = I²R or P = V²/R
Resistors in series
V𝗌 = V₁+V₂+V₃ +… R𝑠 = R₁+R₂+R₃+…
Resistors in parallel
V𝗉 = V₁=V₂=V₃=… 1/R𝗉 = 1/R₁+1/R₂+1/R₃…
Capacitor
has the ability to hold charge at a particular voltage (Ex/ defibrillator)
Capacitance
the ratio of the charge stored on 1 plate to the voltage across the whole capacitor
C = Q/V
C = 𝞮₀ (A/d)
Units in Farad. 1F = 1 C/V
Uniform electric field
Creates a separation of charges
E = V/d
Dielectric material
An insulator. When a insulator is introduced between the plates of a capacitor, the capacitance increases by a factor called the dielectric constant (𝜅).
Capacitors in series and parallel
1/C𝑠 = 1/C₁+1/C₂+1/C₃+… C𝗉 = C₁+C₂+C₃+…
Wave speed
v = fλ —> f = v/λ -> f = c/λ
Wave period
T = 1/f —> f = 1/T
f is in units of cycles/sec or Hz
Range of human ear
Frequencies between 20 and 20,000 Hz
Ultrasonic waves
Frequencies higher than normal human hearing (>20 kHz)
Damping
Also called attenuation. Causes a decrease in the amplitude (an interruption) due to a nonconservative force
Sound wave speed
Sound waves are longitudinal waves that can only be transmitted through a medium (speed through a medium: gas < liquid < solid)
v = √B/𝜌
Doppler effect
fo = f𝘴 (v±vo / v∓v𝘴)
The upper sign is used if the detector or source is moving toward the object
The lower sign is used if the detector or source is moving away from the object
Intensity
I = Power/Area in W/m²
*I = 2π²𝒑𝒇²A²𝐯
Threshold of hearing (I₀)
1 x 10⁻¹² W/m² or 0 dB
Sound level
β = 10 log I(final)/I₀
measured in decibels (dB)
Visible light spectrum
700nm - 400nm (red —> purple)
Electromagnetic spectrum
Radio–>micro–>IR–>visible light–>UV–>X-ray–>Gamma
Speed of light
The speed of light (c) is 3 x 10⁸ m/s
c = λf
Optics (mirror/lens) equation
1/f = 1/o + 1/i = 2/r
Magnification
m = - i/o
If |m| <1 then the image is smaller than the object (reduced)
If |m| >1 then the image is larger than the object (enlarged)
Converging mirrors
Positive focal length (positive power)
- Behind focal point - real, inverted, magnified
- On focal point - no image
- Front focal point - virtual, upright, magnified
Diverging optics
Negative focal length (negative power)
- Object only forms virtual, upright, reduced images (Ex/ parking garage mirrors).
Snell’s law
n = c/v –> n₁sinθ₁ = n₂sinθ₂
- n = index of refraction (refraction is due to wavelength)
- v is the speed in the medium (gas > liquid > solid)
- n and v have an inverse relationship
- 1 is where light is coming from and 2 is where it is entering
Power (optics)
p = 1/f Power is (+) for converging lens and (-) for diverging lens
Hyperoptia
farsightedness
Myopia
nearsightedness
Spherical aberration
Occurs when there is blurring of the periphery of an image
and is the result of inadequate reflection or refraction of parallel beams
Plane polarized light
Light is polarized when the electric and magnetic fields are oriented in a particular (not random) way. It exhibits a particular alignment, separation, or orientation
Florescence
emission of light after the absorption of light
Chromatic aberration
occurs when there is a splitting of white light due to the thickness and curvature of a lens that results in rainbow halos around images
Diffraction
process by which a beam of light or other system of waves is spread out as a result of passing through a narrow aperture or opening
Dispersion
occurs when various wavelengths of light separate from each other after traveling through a medium
Refraction
The bending of light as it moves from one medium to another changing the speed. This has to do based on wavelength (not frequency)
Threshold frequency
fT, the minimum amount of light (photons) that causes ejection of electrons from a metal
where the energy of each photon is E= hf
Plank’s constant
f = Plank’s constant = 6.6 x 10⁻³⁴ J·s
Mass defect
the difference between the sum of all individual nucleons (protons and neutrons) in a nucleus and the actual mass of the nucleus
E = mc²
Binding energy
energy that holds the nucleons together at the low energy level. The difference of energy is radiated away (heat, light, radiation)
Isotopic notation
ᴬzX where A is the mass number (protons+neutrons) and Z is the atomic number (# of protons)
Fusion
occurs when small nuclei combine to form a larger nucleus
Fission
occurs when a large nucleus splits into smaller nuclei
Radioactive decay
ᴬzX —> ᴬzY + decayed particle where X is the parent nucleus and Y is the daughter nucleus. It is a function of isotopes
Alpha decay
The emission of an α-particle (⁴₂He). The daughter nucleus will have 2 less protons than the parent. The mass number will be 4 less
Beta decay
The breakdown of a neutron into a proton and electron and the emission of a newly created electron (⁰-₁e⁻). The mass number stays the same, but the atomic number increases by 1
Positron emission
The emission of a positron (⁰-₁β⁺) when a proton becomes a neutron. This is a type of β decay. A positron can be thought of as an electron with a positive charge (⁰₁e⁻). The mass number will stay the same, but the atomic number will decrease by 1
Gamma decay
Also called gamma ray emission, occurs when an electron and positron collide. It accompanies other types of radioactive decay and does not change the identity of atom from which it is given off
⁰₁e⁻ + ⁰-₁e⁻ -> ⁰₀𝛾 + ⁰₀𝛾
Electron capture
The capture of an electron (⁰-₁e⁻) and the merging of that electron w/ a proton to create a neutron. The mass number of the product stays the same, but the atomic number will decrease by 1. Emission of 𝛾-rays (⁰₀𝛾), which are high frequency photons, occurs also
Half life
The time it takes for half the sample to decay. All atoms other than hydrogen are subject to some type of spontaneous decay.
(1/2)ˣ = y where x = the # of half lives and y = the amount of sample left after time has passed
Exponential decay
Describes how the number of radioactive nuclei changes with time
Variables of half life problems
1) initial amount of substance 2) final amount of substance 3) length of half life 4) the number of half lives
Axis of phase change diagram
Energy on the X axis and temperature on the Y axis
Translational equilibrium
An object is in translational equilibrium when the sum of all the external forces acting on the object equals zero
Force (electric field)
F = qE
Photoelectric effect
When photons strike metal and cause the ejection of electrons
Wavenumber
The inverse of wavelength (λ)
Rigidity
Inversely proportional to the delocalization of e- meaning if a double bond has more resonance structures, it is less rigid. Ex/ ethene is more rigid than ozone
Right hand rule
Point your thumb in the direction of the current and wrap your fingers around the current carrying wire. Your fingers represent the circular field lines, curling around the wire.
Internal resistance
If internal resistance is non-negligible, then the emf of the circuit must be greater than the voltage applied.
V = emf - i·r(internal)
Resonance
When the natural frequency and the driving force are equal
To resonate
vibrate
Heat capacity
C = mc -> q = CΔT = mcΔT
