Pancyprian Physics flashcards
Pancyprian Physics · Build recall with a focused review session.
33 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Centripetal acceleration
- Acceleration of a body moving in a circle at constant speed, directed toward the centre, of magnitude v²/r or ω²r; it changes direction of velocity, not speed.
- Conservation of momentum
- In a system with no net external force, total momentum before an interaction equals total momentum after; applies to all collisions and explosions, elastic or not.
- Impulse
- Product of a force and the time for which it acts, equal to the change in momentum; the area under a force-time graph gives the impulse.
- Simple harmonic motion
- Oscillation in which acceleration is proportional to displacement from equilibrium and directed oppositely, giving a = −ω²x and a sinusoidal displacement-time graph.
- Resonance
- Condition where a periodically driven system oscillates with maximum amplitude because the driving frequency matches the system's natural frequency; damping reduces the peak amplitude.
- Standing wave
- Pattern formed when two identical waves travelling in opposite directions superpose, giving nodes of zero displacement and antinodes of maximum displacement at fixed positions.
- Doppler effect
- Change in observed frequency when source and observer move relative to each other; approaching raises frequency, receding lowers it, for both sound and light.
- Kirchhoff's loop rule
- Around any closed circuit loop, the sum of potential differences is zero; equivalently, the sum of emfs equals the sum of potential drops across components.
- Lenz's law
- The induced current flows in a direction whose magnetic field opposes the change in flux that produced it, a consequence of energy conservation.
- Electric field strength
- Force per unit positive charge at a point, a vector measured in newtons per coulomb or volts per metre; for a point charge E = kQ/r².
- Magnetic flux density
- Magnetic force per unit current per unit length on a conductor placed at right angles to the field; measured in tesla, one T equals one N A⁻¹ m⁻¹.
- Internal energy
- Sum of the random kinetic and potential energies of all particles in a system; for an ideal gas it depends only on thermodynamic temperature.
- Specific latent heat
- Energy needed to change the phase of one kilogram of a substance at constant temperature, without any change in temperature during the process.
- First law of thermodynamics
- Change in internal energy equals heat added to the system minus work done by the system; a statement of energy conservation for thermal processes.
- Carnot efficiency
- Maximum possible efficiency of a heat engine operating between hot and cold reservoirs at absolute temperatures T_H and T_C, equal to 1 − T_C/T_H.
- Total internal reflection
- Complete reflection of light at a boundary when travelling from a denser to a rarer medium and the angle of incidence exceeds the critical angle.
- Critical angle
- Angle of incidence in the denser medium for which the refracted ray grazes the boundary at 90 degrees; given by sin C = n₂/n₁.
- Fringe spacing
- Separation of adjacent bright or dark fringes in a double-slit pattern, equal to λD/d where D is slit-to-screen distance and d is slit separation.
- Diffraction grating equation
- d sinθ = nλ gives the angles θ of principal maxima for grating spacing d, order n and wavelength λ; larger n gives larger angles.
- Work function
- Minimum energy needed to remove an electron from the surface of a metal; determines the threshold frequency below which no photoelectric emission occurs.
- Stopping potential
- Reverse potential difference just sufficient to stop the fastest photoelectrons, so that eV_s equals the maximum kinetic energy of emission.
- Half-life
- Time for half the nuclei in a radioactive sample to decay; independent of sample size, related to decay constant by T½ = ln2/λ.
- de Broglie wavelength
- Wavelength associated with a moving particle, equal to Planck's constant divided by its momentum; significant only for very small masses.
- Mass defect
- Difference between the total mass of separate nucleons and the mass of the assembled nucleus; multiplied by c² it gives the binding energy.
- Archimedes' principle
- Upthrust on a body in a fluid equals the weight of fluid displaced; a floating body displaces fluid whose weight equals its own weight.
- Bernoulli's equation
- Along a streamline in steady incompressible flow, pressure plus kinetic energy density plus gravitational potential energy density per unit volume remains constant.
- Terminal velocity
- Constant speed reached by a falling body when the upward viscous drag plus upthrust equals its weight, so net force and acceleration become zero.
- Young's modulus
- Ratio of tensile stress to tensile strain in the linear elastic region of a material; a measure of stiffness, measured in pascals.
- Elastic limit
- The greatest stress a material can bear and still return to its original shape when the load is removed; beyond it permanent deformation occurs.
- Percentage uncertainty
- Absolute uncertainty divided by the measured value, expressed as a percentage; percentage uncertainties add when quantities are multiplied or divided.
- Systematic error
- A consistent shift of all readings from the true value, caused by instrument zero error or faulty calibration; it is not reduced by taking repeated readings.
- Line of best fit
- Straight line drawn through a data set so that points are balanced above and below it; its gradient and intercept are extracted with uncertainties.
- Significant figures
- Digits in a measurement that carry meaning about its precision; a calculated result should not exceed the significant figures of the least precise input.