Physics and Math Flashcards
Half-Life
The amount of time it takes for one-half of a radioactive sample to decay, given by the equation: T1/2= ln2/lambda.
Adhesion
A type of attractive force that molecules of a liquid feel toward molecules of another substance, such as in the adhesion of water droplets to a glass surface.
Alpha Decay
A nuclear reaction in which an alpha particle is emitted.
A A-4 4
X => Y + He
Z Z-2 2
Beta Decay
A nuclear reaction in which a B-particle is emitted:
A A
X => Y + B-
Z Z+1
Capacitor
An electric device used in circuits that is composed of two conducting plates separated by a short distance; these devices store electric charge
Center of Mass
The point on some object or body where all of its mass is considered to be concentrated. In a uniform gravitational field, this is also the center of gravity.
Cohesion
A type of attractive force felt by liquid molecules toward each other. Cohesion is responsible for surface tension.
Conductor
A material in which electrons can move with relative ease.
Conservative Force
A force that does not cause dissipation of mechanical energy from a system. As such, the work perfromed is independent of the path taken. Examples include gravity and electrostatic forces. Elastic forces are nearly conservative.
Convection
Form of heat transfer where a heated fluid transfers energy by bulk flow and physical motion over another object, or a cooled fluid absorbs energy by the same means.
Density
A scalar quantity defined as mass per unit volume, often denoted by p. Density of an object may be compared to water as a unitless quantity known as specific gravity.
Direct Relationship
A relationship between variables such that an increase in one variable is associated with an increase in the other:
A/B = constant.
Dispersion
The phenomenon observed when white light is incident on the face of a prism and emerges on the opposite side with all its wavelengths split apart, forming the visible spectrum. This occurs because wavelength (l) is related wo the index of refraction by the expression n=c/fl
Displacement
A vector quantity describing the straight-line distance between an initial and a final position of some particle or object.
Electric Circuit
A conducting pathway that contains one or more voltage sources that drive an electric current along that pathway and through connected passive circuit elements (such as resistors).
Electromagnetic Spectrum
The full range of frequencies and wavelengths for electromagnetic waves broken down into the following regions (in descending order of wavelength): radio, infrared, visible light, ultraviolet, X-ray, and gamma ray.
Electromagnetic Waves
When an electric field is changing, it causes a change in a magnetic field and vice versa, resultingin the propagation of a wave containing an electric and a magnetic field that are perpendicular to each other.
Electromotive Force
The impetus for current flow created by a voltage source, such as a battery or outlet. Electromotive force is measured in volts (V).
Equipotential Lines
Concentric circles emanating from a source charge that cross its electric field lines perpendicularly. No work is required for a test charge to travel along the circumference of an equipotential line, because the potential at every point along that line is the same.
Focal Length
The distance between the focal point and the mirror or lens. For spherical mirrors, the focal length is equal to one-half the radius of curvature.
Force
A vector quantity describing the push or pull on an object. The SI unit for force is the newton (N).
Frequency
Number of cycles per second measured in units of Hz, where 1 Hz = 1 cycle per second.
Gamma Decay
A nuclear reaction in which high-energy photons, also known as gamma particles, are emitted:
A A
X* => X + gamma
Z Z
Heat Transfer
The movement of thermal energy toward a state of thermodynamic equilibrium. Heat spontaneously transfers energy from the object with the higher temperature to the object with the lower temperature.
Image
The apparent location of an object perceived through a lens or mirror. An image produced at a point where light does not actually pass through or converge is called a virtual image. An image produced at a point where the light rays actually converge or pass through is called a real image.
Insulator
A material in which electrons cannot move freely.
Interference
When superimposed waves are in phase, their amplitudes add (constructive interference). When superimposed light waves are out of phase, their amplitudes subtract (destructive interference).
Inverse Relationship
A relationship between variables such that an increase in one variable is associated with a decrease in the other: AB=constant
Kirchhoff’s Junction Rule
States the sum of the currents directed into a node or junction point in a circuit equals the sum of the currents directed away from that point.
Laminar flow
The smoothest type of liquid flow through a tube wherein thin layers of liquid slide over one another. Occurs as long as the linear flow speed remains below a critical speed vc. Laminar flow can be represented by roughly parallel streamlines- lines that trace the path of water particles as they flow in a tube without ever crossing each other.
Law of Reflection
States that when light waves strike a medium, the angle of incidence is equal to the angle of reflection.
Lens
A transparent device with a curvature that causes light to bend (refract) as it passes through. May be converging or diverging. A lens with a thick center that converges light rays at a point where the image is formed is called a converging lens. A lens with a thin center that diverges light after refraction and always forms a virtual image is called a diverging lens.
Logarithm
A mathematical function that is the inverse of the exponentiation function. Logarithms with base ten are called common logarithms; logarithms with Euler’s number (e=2.72) are called natural logarithms (ln).
Mass
A scalar quantity used a measure of an object’s inertia. The SI unit of mass is the kilogram (kg).
Newton’s First Law
States that if no net force acts on an object, its velocity is constant.
Newton’s Second Law
States that an object will accelerate in proportion to the net force acting on it:
Fnet = ma
Newton’s Third Law
States that if no one objects exerts a force on another, the other object exerts a force on the first that is equal in magnitude but opposite in direction; the law of “action and reaction”.
Nonconservative Force
A force that dissipates mechanical energy from a system. As such, the energy dissipated depends on the path taken from initial to final position. Examples include friction, air resistance, and viscous drag.
Normal Force
Perpendicular component. of the force caused when two surfaces push against each other, denoted by N.
Plane Mirror
A mirror in which incident light rays remain parallel after reflection, always producing a virtual image that appears to be the same distance behind the mirror as the object is in front of the mirror.
Plane-Polarized Light
Light that has been passed through a polarizing filter, allowing only the transmission of waves containing electric field vectors parallel to the lines of the filter.
Positron Decay
A nuclear reaction in which a positron is emitted:
A A
X => Y + B+
Z Z-1
Potential Difference
The difference in electric potential between two points in an electric field.
Radiation
Form of heat transfer where the energy is carried by electromagnetic waves; the only form of heat transfer that can be carried out in a vacuum.
Resistance
The natural tendency of a conductor to block current flow to a certain extent resulting in loss of energy or potential. Resistance is equal to the ratio of the voltage applied to the resulting current. The SI unit for resistance is the ohm.
Right-Hand Rule
A common method used to determine the direction of a vector created as the product of two vectors. The thumb points in the direction of the first vector, the fingers point in the direction of the second vector, and the palm points in the direction of the resultant.
Rotational Equilibrium
State where the sum of the torques acting on a body is zero, giving it no net angular acceleration. An object may be in rotational equilibrium, translational equilibrium, or both simultaneously.
Scalar
A quantity that has magnitude but no direction
Second Law of Thermodynamics
States that for any process, the entropy of the universe either increases (for irreversible processes) or remains constant (for reversible processes).
Speed
A scalar quantity describing the distance traveled divided by the time required to travel that distance. The SI unit of speed is meters per second (m/s)
Spherical Mirror
Spherical mirrors have the appearance of a curved surface that is either concave or convex. A converging mirror is a concave mirror with a positive focal length, while a diverging mirror is a convex mirror with a negative focal length. Diverging mirrors always produce virtual images.
Total Internal Reflection
The condition in which the incident angle of light traveling from a medium with a high n to a medium with a low n is greater than the critical angle. This results in all of the light being reflected and none of it being refracted.
Translational Equilibrium
State where the sum of the forces acting on an object is zero, giving it no net acceleration. An object may be in rotational equilibrium, or both simultaneously.
Turbulent Flow
Type of liquid flow that occurs when the linear flow speed in a tube exceeds the critical speed vc. The motion of the fluid that is not adjacent to the container walls is highly irregular, forming vortices and a high resistance.
Vector
A quantity that has both magnitude and direction.
Viscosity
The measure of internal friction in a fluid, often denoted by n. Viscosity is responsible for creating viscous drag, a nonconservative force analogous to air resistance.
Wavelength
A quantity equal to the distance between any two equivalent consecutive points along a wave, such as two consecutive crests (peaks) or two consecutive troughs (valleys); expressed as wavelength. The SI unit of wavelength is the meter (m).
Torque
A force creating rotation about an axis; measured as the lever arm (the distance between the fulcrum and the applied force) times the magnitude of the force times the sine of the angle between them:
T = rF sin(theta). The SI unit of torque is the newton meter (N x m).
Conservation of Mechanical Energy
States that when only conservative forces act on an object and work is done, energy is conserved and described by the equation:
E = U + K = 0
Acceleration
A vector quantity describing a change in velocity over the elapsed time during which that change occurs, expressed as
a = v/t
The SU unit of acceleration is m/s^2.
Doppler Effect
f’ = f (v +/- vD) / (v +/- vS)
Frictional Force
An antagonistic force that points parallel and opposite in direction of movement of an object.
0 < static friction <
(Static coefficient)(N)
Kinetic friction =
(Kinetic coefficient)(N)
Gravitational Potential Energy
The energy of an object due to its height above a given datum, calculated by the equation U = mgh.
SI unit is Joules (J).
Gravity
Fg = Gm1m2 / r^2
Gravity is a force and measured in Newtons (N).
Kinetic Energy
The energy of an object in motion.
K = 1/2mv^2 (Joules)
Magnification
m=-i/o
i is the image distance and o is the object distance. A negative m denoted inverted image, whereas a positive m denotes an upright image.
Ohm’s Law
Law stating that the voltage drop across a resistor is proportional to the current flowing through it, given by the equation V= IR. (volts)
Power
The rate at which work is done, given by the equation P = W/t, where W is work and t is time (seconds). The SI unit for power is the watt (W).
Pressure
The force per unit area:
P = F/A. May be provided as absolute pressure, which is the pressure below the surface of a fluid that depends on gravity and surface pressure, calculated by
P = P0 - pgz, where P is the absolute pressure, P0 is the pressure at the surface, p is the density of the fluid, g is the acceleration due to gravity, and z is depth. The SI unit for pressure is the pascal (Pa).
Speed of Light
c = (wavelength) x (frequency)
c = 3.00 x 10^8 m/s
Velocity
v = x/t
SI unit is meters/second.
Wave Speed
v = (frequency) x (wavelength)
Work
One of the two forms of energy transfer in which a force is applied to change the energy of a system. In mechanics, commonly calculated by the equation W = Fdcos(theta), where F is the magnitude of the applied force, d is the magnitude of the displacement, and theta is the angle between these two vectors. The SI unit of work is the joule (J).
Conduction
Form of heat transfer where energy is transferred by molecular collisions or direct contact between two objects.
Pascal’s Principle
States that when a pressure is applied to one point of an enclosed fluid, that pressure is transmitted in equal magnitude to all points within that fluid and to the walls of its container. This principle forms the basis of the hydraulic lift.
Dielectric
An insulating material placed between the two plates of a capacitor; used to increase capacitance. If the circuit is plugged into a current source, more charge will be stored. If the circuit is not plugged in, the voltage of the capacitor will decrease, indirectly increasing its capacitance. The strength of a dielectric is measured by the dielectric constant.
Diffraction
The spreading-out effect of light when it passes through a small slit opening.
Kirchhoff’s Loop Rule
States that the sum of the voltage sources in a circuit loop is equal to the sum of voltage drops along that loop.
Mass Defect
The difference between an atom’s atomic mass and the sum of the masses of its proton and neutrons.
Work-Energy Theorem
States that the net work performed on an object is related to its change in energy. In most applications, the work-energy theorem is used to relate work and kinetic energy.
Zeroth Law of Thermodynamics
States that two objects that are in thermal equilibrium with a third object are also in thermal equilibrium with each other. By extension, objects at the same temperature are in thermal equilibrium with no net transfer of heat.
Electric Power
The rate at which the energy of flowing charges through a resistor or other device is dissipated, given by the equation P = IV.
SI unit of power is Watt (W).
First Law of Thermodynamics
States that the change in internal energy of a system is equal to the heat transferred into the system minus the work done by the system:
U = Q - W.
An extension of the law of conservation of energy.
Photoelectric Effect
The phenomenon observed when light of a certain frequency causes a metal to emit electrons. The minimum amount of energy required to emit an electron from a certain metal is called the work function. This quantity, denoted by W, is used to calculate the residual kinetic energy of an electron emitted by a metal, given by:
K = hf - W
Archimedes’ Principle
States that a body that is fully or partially immersed in a liquid will be buoyed upwards by a force that is equal to the weight of the liquid displaced by the body.
Fbouy = (pfluid) x (Vsubmerged) x (g)
Bernoulli’s Equation
P1 + 1/2pv^2 + pgh1 =
P2 + 1/2pv^2 + pgh2
Binding Energy
The energy that holds the protons and neutrons together in the nucleus, defined by the equation
E = mc^2, where m is the mass defect and c is the speed of light in a vacuum.
Capacitance
A measure of a capacitor’s ability to store charge at a given voltage; calculated by the ratio of the magnitude of charge on one plate to the voltage across the two plates:
C = Q / V.
The SI unit for capacitance is the farad (F).
Centripetal Acceleration
ac = (v^2) / r
Continuity Equation
States that the mass flow rate of fluid must remain constant from one cross-section of a tube to another, given by A1v1 = A2V2
Coulomb’s Law
The law describing the electrostatic force that exists between two charges, q1 and q2, that are separated by a distance r. Given by the equation F = k(q1)(q2) / (r^2)
Current
A flow of charge per time.
I = q/t.
The SI unit of current is the ampere (A).
Elastic Potential Energy
The energy associated with stretching or compressing a spring, calculated by the equation
U = 1/2kx^2 and given in the SI unit of Joules (J)
Electric Field
The Electrostatic force that a source charge would exert on a positive test charge q0 divided by the magnitude of that test charge:
E = F/q0. Electric fields are represented by electric field lines- imaginary lines that show the direction in which a positive test charge is accelerated by the coulombic force due to the electric field of a source charge. The SI unit of electric field strength is N/C or V/m.
Electric Potential
The amount of electric potential energy per unit charge; the work required to bring a positive test charge q0 from infinity to within an electric field of another positive source charge, Q, divided by that test charge’s magnitude. Calculated by the equation V = kQ/r.
The SI unit of electric potential is the volt (V).
Electric Potential Energy
The amount of work required to bring a test charge q0 from infinity to a point within the electric field of some source charge Q, given by the equation U = q0V.
The SI unit of electric potential energy is the joules (J).
Exponential Decay
A decrease in the amount of substance N at an exponential rate. Given by the equation:
N = N0 x e^-lt
Gauge Pressure
The pressure above and beyond atmospheric pressure, the gauge pressure is given by pgz, where p is the density of fluid, g is acceleration due to gravity, and z is depth. The SI unit of pressure is the pascal (Pa).
Heat of Transformation
The amount of heat required to change the phase of a substance, calculated by the equation q=mL, where q is heat, m is the mass of the substance, and L is the heat of transformation for that substance. The heat of transformation corresponding to the solid-liquid phase change is called the heat of fusion; that corresponding to liquid-gas is called the heat of vaporization.
Index of Refraction
Ratio of the speed of light in a vacuum to the speed of light through a medium, given by n = c/v
Resistivity
Intrinsic property of a conductor used to measure its resistance in the equation R = pL/A, where R is the resistance, p is the resistivity, L is the length of the conductor, and A is its cross-sectional area. The SI unit of resistivity is the ohm-meter.
Snell’s Law
n1sin(theta1) = n2sin(theta2)
Sound Level
The loudness of a sound, measured in decibels (dB) and denoted by B. Given by the equation B=10log(l/lo), where I is the intensity of the sound and Io is a reference intensity of 10^-12 W/m^2
