All OCR A A Level Physics Defination paper

All OCR A A Level Physics Definitions Paper What are the SI base units? - Correct Answer Metre, kilogram, ampere, mole, second, kelvin Scalar quantity - Correct Answer Has magnitude but no direction Vector quantity - Correct Answer Has both magnitude and direction Acceleration - Correct Answer rate of change of velocity Define the Newton - Correct Answer the force that causes a mass of 1kg to have an acceleration of 1ms^-2 in the direction of the force Tension - Correct Answer The force within a stretched cable or rope Normal contact force - Correct Answer The force that arises when one object rests against another Upthrust - Correct Answer An upward buoyancy force acting on an object when it is in a fluid Friction - Correct Answer A force that opposes motion between two surfaces that are in contact Drag - Correct Answer The frictional force experienced by an object travelling through a fluid moment - Correct Answer Force x perpendicular distance from point of rotation Principle of moments - Correct Answer For a body in rotational equilibrium, the sum of the anticlockwise moments about a point is equal to the sum of the clockwise moments about the same point Centre of gravity - Correct Answer The point where the entire weight of an object appears to act. Centre of mass - Correct Answer A point through which any externally applied force produces straight-line motion but no rotation Torque - Correct Answer one of the forces x perpendicular separation between the forces Density - Correct Answer Mass per unit volume Pressure - Correct Answer Force per unit area. Pressure in a fluid at any depth... - Correct Answer same in all directions Archimede's Principle - Correct Answer The upthrust exerted n a body immersed in a fluid, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces Joule - Correct Answer 1 Nm Energy - Correct Answer the capacity to do work Principle of conservation of energy - Correct Answer The total energy of a closed system remains constant; energy can not be created or destroyed, only transferred from one form to another Power - Correct Answer the rate at which work is done Watt - Correct Answer One joule per second Hooke's Law - Correct Answer The extension of a spring is directly proportional to the force applied, as long as the elastic limit is not exceeded Tensile stress - Correct Answer Force per unit cross-sectional area Tensile strain - Correct Answer The fractional change in the original length of the wire Ultimate tensile strength - Correct Answer The maximum stress that a material can withstand before it breaks Young Modulus - Correct Answer The ratio of stress to strain for a particular material Newton's First Law - Correct Answer An object will remain at rest or continue to move at a constant velocity, unless acted upon by a resultant force Newton's Third Law - Correct Answer When two objects interact they exert equal and opposite forces on each other (of the same type, and never on same object) Conservation of momentum - Correct Answer For a system of interacting objects, the total momentum in a specified direction remains constant, as long as no external forces act on the system Perfectly elastic collision - Correct Answer A collision where total kinetic energy is conserved Inelastic collision - Correct Answer Collision where total kinetic energy is not conserved Newton's Second Law - Correct Answer The net force acting on an object is directly proportional to the rate of change of its momentum, and is in the same direction Impulse of a force - Correct Answer change in momentum Thermal equilibrium - Correct Answer Net flow of thermal energy between objects is zero Kinetic model of solids - Correct Answer Atoms or molecules regularly arranged and packed closely together, with strong forces of electrostatic attraction between them holding the m in fixed positions, but they can vibrate so have kinetic energy Kinetic model of liquids - Correct Answer Atoms or molecules still close together, but have more kinetic energy than solids, they can change position and flow past each other Kinetic model of gases - Correct Answer Atoms or molecules have more kinetic energy than liquids, and are much further apart. Free to move past each other as negligible electrostatic forces of attraction between them unless they collide with each other or container walls. Move randomly with different speeds in different directions. Brownian motion observations - Correct Answer Particles move randomly, smoke particles much larger than air molecules Inernal Energy of a Substance - Correct Answer The sum of the randomly distributed kinetic and potential energies of atoms or molecules within a substance Electrostatic potential energy... - Correct Answer Zero in gases, more negative in liquids, most negative in solids Why are electrostatic potential energies negative? - Correct Answer Energy must be supplied to break atomic or molecular bonds At absolute zero.... - Correct Answer Internal energy is minimum Specific heat capacity - Correct Answer The energy per unit mass required to change the temperature by 1K Specific latent heat - Correct Answer Energy supplied to change the phase of a mass of a substance Specific latent heat of fusion - Correct Answer the energy needed to change a unit mass from the solid to the liquid phase at constant temperature Specific latent heat of vaporisation - Correct Answer the energy needed to change a unit mass from the liquid to the gas phase at constant temperature One mole - Correct Answer The amount of substance that contains as many elementary entities as there are atoms in 12g of Carbon-12 Kinetic theory of gases assumptions - Correct Answer Very large number of atoms or molecules moving in random directions with random speeds, occupy a negligible volume compared with the volume of the gas, collins with each other and the container walls are perfectly elastic, time of collisions between atoms with each other or container walls is negligible compared to the time between the collisions, electrostatic forces negligible except during collisions Boyle's Law - Correct Answer If the temperature and mass of a gas is constant, its pressure is inversely proportional to its volume Relationship between pressure and temperature of an ideal gas - Correct Answer If the volume and mass of a gas is constant, its pressure is directly proportional to its temperature Internal energy of an ideal gas - Correct Answer Entirely in the form of kinetic energy and electrostatic forces between atoms or molecules are negligible The radian - Correct Answer The angle subtended by a circular arc with length equal to the radius of the circle Degrees to radians conversion - Correct Answer Divide angle in degrees by π/180 Angular velocity - Correct Answer rate of change of angular displacement For body to move in a circular path with a constant velocity - Correct Answer Resultant force must be perpendicular to the velocity so no force in direction of motion; no work done on object OM; displacement - Correct Answer Distance from the equilibrium position OM; amplitude - Correct Answer Maximum displacement from the equilibrium position Om; period - Correct Answer The time taken for one complete oscillation OM; frequency - Correct Answer The number of oscillations per unit time Simple harmonic motion - Correct Answer Oscillating motion where acceleration is directly proportional to displacement and directed towards a fixed point Isochronous oscillator - Correct Answer An oscillator that has the same period regardless of amplitude Free oscillation - Correct Answer When a mechanical system is displaced from its equilibrium position and allowed to oscillate without any external forces Forced oscillation - Correct Answer An oscillation in which a periodic driver force is applied to an oscillator Frequency of free oscillation - Correct Answer Natural frequency Frequency of forced oscillation - Correct Answer Driving frequency Resonance - Correct Answer When the driving frequency is equal to the natural frequency, amplitude of oscillation increases significantly and if not damped system may break Gravitational field strength - Correct Answer Force exerted per unit mass Newton's Law of Gravitation - Correct Answer The force between two point masses is directly proportional to the product of the two masses and inversely proportional to the square of the separation Kepler's First Law - Correct Answer The orbit of a planet is an ellipse, with the sun at of of the two foci Kepler's Second Law - Correct Answer A line segment joining a planet and the sun sweeps out equal areas in equal intervals of time Kepler's Third Law - Correct Answer The square of the orbital period of a planet is directly proportional to the cube of its average distance from the sun Uses of satellites - Correct Answer Communications, GPS, weather monitoring Geostationary satellites - Correct Answer Equatorial orbit, rotate in sae direction as earth's rotation, have an orbital period of 24 hours Gravitational potential - Correct Answer Work done per unit mass in bringing an object from infinity to a point Escape velocity - Correct Answer the minimum velocity needed to escape a gravitational field Planet - Correct Answer An object in orbit around a star that has a mass large enough for its own gravity to give it a round shape, has no fusion reactions, and has cleared its orbit of most other objects Planetary satellites - Correct Answer A body in orbit around a planet Comet - Correct Answer Small, irregular bodies made up of ice and dust and small pieces of rock, in orbit around the sun Solar system - Correct Answer The sun and all the objects that orbit it Galaxy - Correct Answer A collection of stars, and interstellar dust and gas Electron degeneracy pressure - Correct Answer When core of a star begins to collapse under the fore of gravity, electrons are squeezed together which creates pressure that prevents core from further gravitational collapse Chandrasekhar limit - Correct Answer electron degeneracy pressure is only sufficient to prevent gravitational collapse if the core has a mass less than 1.44 solar masses Neutron star - Correct Answer Very small, very dense star that remains after a supernova Black hole - Correct Answer Very dense, gravitational field so strong light cannot escape it Emission line spectra - Correct Answer Each element produces a unique emission line spectrum because of its unique set of energy levels Continuous spectra - Correct Answer All visible frequencies or wavelengths are present. Absorption line spectra - Correct Answer dark spectral lines against a continuous spectrum Wien's displacement law - Correct Answer Maximum wavelength is inversely proportional to temperature Stefan's law - Correct Answer The total power radiated per unit surface area of a black body is directly proportional to the fourth power of the absolute temperature of the black body Astronomical unit - Correct Answer The average distance from the earth to the sun Light year - Correct Answer The distance travelled by light tin a vacuum in the time of one year Parsec - Correct Answer The distance at which a radius of 1 AU subtends an angle of 1 arc second Stellar parallax - Correct Answer The apparent shift in the position of a nearby star against a backdrop of much more distant stars as the earth orbits the sun The doppler effect - Correct Answer Whenever a wave source moves relative to an observer, the frequency and wavelength of the waves received by the observer change, compared to what would be observed without relative motion Hubble's Law - Correct Answer The recessional speed of a galaxy is almost directly proportional to its distance from the earth Hubble's observations - Correct Answer Light from the majority of galaxies is red shifted, so relative velocity away from earth and the further away the galaxy the greater the red shift, so the faster the galaxy was moving Cosmological principle - Correct Answer When viewed on a large enough scale, the universe is homogenous and isotropic, and the laws of physics are universal Homogeneous - Correct Answer Matter is distributed uniformly across the universe Isotropic - Correct Answer The universe looks the same in all directions to every observer Evidence for the big bang - Correct Answer Hubble's law and microwave background radiation Brownian motion observation and conclusion - Correct Answer Particles move randomly due to collisions