OCR A A-Level Physics Paper 1 with Correct Answers 100% verified 2025

Displacement - Correct Answer The distance travelled in a particular direction - it is a vector with magnitude and direction. Instantaneous Speed - Correct Answer The rate of change of distance at a specific moment in time - change in distance divided by an infinitesimal interval of time. Average Speed - Correct Answer The rate of change of distance calculated over a complete journey Velocity - Correct Answer A vector quantity equal to the rate of change of displacement. Average Velocity - Correct Answer The change in displacement (Δs) for a journey divided by the time taken (Δt). Acceleration - Correct Answer A vector quantity equal to the rate of change of velocity. Stopping distance - Correct Answer The distance travelled until the car stops (thinking distance + braking distance) Thinking distance - Correct Answer Distance travelled while the driver reacts Braking distance - Correct Answer The distance travelled between the instant the brakes are applied and the instant the vehicle stops completely. Free fall - Correct Answer The motion of an object accelerating under gravity with no other (significant) forces acting Projectile - Correct Answer An object that is thrown or propelled on the surface of the Earth Time of flight - Correct Answer The duration of an object's free movement through a fluid Weight - Correct Answer The gravitational force on an object, measured in Newtons, N. Centre of gravity - Correct Answer Point on an object where all forces can be assumed to act Plumb-line - Correct Answer A string with a weight used to provide a vertical reference line. Free-body diagram - Correct Answer A diagram that represents all the forces acting on a single object. Normal contact force - Correct Answer The perpendicular force exerted by a surface on an object. Drag force - Correct Answer The resistive force exerted by a fluid on an object moving through it. Terminal velocity - Correct Answer The maximum velocity reached when an object's weight is equal to the drag force acting on it. Moment - Correct Answer Force multiplied by perpendicular distance from pivot Pivot - Correct Answer A point about which a body can rotate. Equilibrium - Correct Answer A body is in equilibrium when the net force and net moment acting on it are zero. Principle of moments - Correct Answer For a system in equilibrium, the sum of the clockwise moments about a point is equal to the sum of the anticlockwise moments about the point Couple - Correct Answer A pair of equal and opposite forces acting on a body but not in the same straight line. Torque - Correct Answer The moment of a couple. Magnitude of one of the forces times the perpendicular distance between them. Tension - Correct Answer The pulling force exerted by a string, cable, or a chain on an object. Triangle of forces - Correct Answer Three forces acting at a point in equilibrium, represented by the sides of a closed triangle. Density - Correct Answer Mass per unit volume Pressure - Correct Answer Force per unit area Fluid - Correct Answer Liquid or gas Upthrust - Correct Answer The upward buoyant force exerted on a body immersed in a fluid. Archimedes' principle - Correct Answer The upthrust experienced by an object in a fluid is equal to the weight of fluid that the object displaces Work - Correct Answer Mechanical energy transfer - force times distance in the direction of the force applied. Gravitational potential energy - Correct Answer The capacity of an object for doing work as a result of its position in a gravitational field. Kinetic energy - Correct Answer The energy associated with an object as a result of its motion. Given by equation Ek=12mv2, where m is mass and v is velocity. Conservation of energy - Correct Answer The principle that energy cannot be destroyed or created but can be transferred between different stores. Uniform gravitational field - Correct Answer Gravitational field where all the field lines are parallel Power - Correct Answer Rate of energy transfer Efficiency - Correct Answer The percentage of power or energy applied that goes into its intended use Extension - Correct Answer The increase in the length of an object when a tensile force is exerted on it Tensile forces - Correct Answer Equal and opposite forces acting on an object to stretch it Compressive forces - Correct Answer Equal and opposite forces acting on an object to reduce its length or volume Tensile deformation - Correct Answer A change in the shape of an object due to tensile forces Compressive deformation - Correct Answer A change in the shape of an object due to compressive forces Elastic limit - Correct Answer The value of stress or force beyond which elastic deformation becomes plastic deformation Elastic deformation - Correct Answer A reversible change in the shape of an object due to a compressive or tensile force - removal of force will return the object to its original size and shape Plastic deformation - Correct Answer Permanent change to the shape of an object due to a compressive or tensile force Hooke's law - Correct Answer Force applied is directly proportional to the extension Force constant - Correct Answer Measure of stiffness of a spring Stiffness - Correct Answer The ability of an object to resist deformation Elastic potential energy - Correct Answer The energy stored in an object because of its deformation Loading curve - Correct Answer A force extension graph or stress strain graph Hysteresis loop - Correct Answer A loading curve obtained when the material in question deforms in different ways when being loaded and unloaded Tensile stress - Correct Answer Force applied per unit cross sectional area Tensile strain - Correct Answer Extension per unit length Limit of proportionality - Correct Answer The value of stress beyond which stress is no longer directly proportional to strain Yield points - Correct Answer A point on stress strain graph beyond which the deformation is no longer entirely elastic Ultimate tensile strength - Correct Answer The maximum stress that a material can withstand before it breaks Breaking point - Correct Answer The point where the UTS has been exceeded Young modulus - Correct Answer Ratio of tensile stress to strain Strong - Correct Answer A material with a large value for the ultimate tensile strength Brittle - Correct Answer Property of a material that does not show plastic deformation and deforms very little under high stress Ductile - Correct Answer Property of a material that has a large plastic region in a stress strain graph, so can be drawn into wires Polymeric - Correct Answer Description of a material comprising of long chain molecules, such as rubber, which may show large strains Newton's first law of motion - Correct Answer A body will continue to remain at rest or move with an constant velocity unless acted on by a resultant force Newton's second law of motion - Correct Answer The rate of change of momentum of an object is directly proportional to the resultant force and in the same direction as the resultant force Newton's third law of motion - Correct Answer If object A exerts a force on object B, object B will exert an equal and opposite force on object A Closed system - Correct Answer An isolated system with no interaction with the surroundings Conservation of momentum - Correct Answer The sum of the momentum of all the bodies in a closed system remains constant over time Elastic collision - Correct Answer A collision where kinetic energy is conserved Inelastic collision - Correct Answer A collision where some of the kinetic energy is transferred into other forms of energy Impulse - Correct Answer The change in momentum of an object Triple point - Correct Answer Temperature and pressure in which the solid, liquid and vapour phase of the pure substance can coexist in equilibrium. Phase - Correct Answer The phase of matter is the state it is in, for example solid. Thermal equilibrium - Correct Answer When two substances in physical contact are the same temperature, so no longer exchange heat energy Absolute scale of temperature - Correct Answer A scale for measuring temperature based on absolute zero and the triple point of pure water, with graduations in equal size to those in the celsius scale. The unit is kelvin (K). Absolute zero - Correct Answer The lowest possible temperature, the temperature at which substances have minimum internal energy. Kinetic model - Correct Answer A model that describes all substances as made of particles (atoms, ions or molecules) arranged differently depending on the phase of the substance. Internal energy - Correct Answer Sum of the random potential and kinetic energies of particles in an object. Specific heat capacity - Correct Answer The energy required to raise the temperature of 1kg of a substance by 1K Specific latent heat - Correct Answer The energy required to change the phase of 1kg of a substance Amount - Correct Answer Number of moles of a substance Avogadro constant, NA - Correct Answer 6.02x1023 mol-1, the number of atoms in 0.012kg of carbon-12 Ideal gas - Correct Answer A theoretical model of a gas Ideal Gas Assumptions - Correct Answer 1. Particles have negligible volume compared with total volume 2. Particles are identical 3. All collisions are elastic 4. No inter molecular forces 5. There are a statistically large number of particles Gas laws - Correct Answer The laws governing the behaviour of all ideal gases Molar gas constant (R) - Correct Answer The constant in the equation of state of an ideal gas (8.31J/Kmol) Equation of state - Correct Answer pV=nRT, where n is the number of moles of gas Root mean square speed - Correct Answer The square root of the mean of speed squared of each particle in a gas Maxwell Boltzmann distribution - Correct Answer The distribution of the speeds of particles in a gas Boltzmann constant (k) - Correct Answer Constant that relates the mean kinetic energy of atoms in the gas to the temperature of the gas (1.38×10^-23J/K) Value of R - Correct Answer 8.31J/Kmol Value of k - Correct Answer 1.38×10^-23J/K k - Correct Answer Symbol for the Boltzmann Constant R - Correct Answer Symbol for molar gas constant Radian - Correct Answer The angle subtended by a circular arc with length equal to the radius of the circle Frequency - Correct Answer The number of complete cycles per unit time, usually measured in Hertz Period - Correct Answer The time taken for one complete cycle Angular displacement - Correct Answer The angle an object has moved through measured from its starting location, measured in radians Angular velocity - Correct Answer The rate of change of angular displacement, usually measured in radians per second Linear velocity - Correct Answer The rate of change of linear displacement, i.e. the velocity an object would have if it were to continue in a straight line at its current speed Centripetal acceleration - Correct Answer The acceleration required for an object to move in a circle, which is always directed towards the centre of the circle Centripetal force - Correct Answer The name given to the resultant force required for an object to move in a circle, which is always directed towards the centre of the circle Point mass - Correct Answer A mass with negligible volume Gravitational field - Correct Answer A field created around any object with mass, extending to infinity but decreasing with distance following the inverse square law. Any object in a gravitational field will experience a force proportional to its mass Gravitational field lines - Correct Answer Lines of force used to map the gravitational field pattern around an object with mass Uniform Gravitational Field - Correct Answer A gravitational field in which the field lines are parallel and the value for g remains constant Radial field - Correct Answer A symmetrical field that diminishes with distance squared from its centre, such as the gravitational field around a spherical mass Gravitational field strength - Correct Answer Gravitational force per unit mass at a point within a gravitational field, units Nkg-1 Gravitational Force - Correct Answer Force due to a gravitational field acting on an object's mass Gravitational Constant, G - Correct Answer Constant of proportionality used in Newton's Law of Gravitation Value of G - Correct Answer 6.673 x10-11 m3kg-1s-2 Newton's Law of Gravitation - Correct Answer The force between two point masses is directly proportional to the product of the masses and inversely proportional to the square of the separation between them; F = -GMm/r^2 Geostationary orbit - Correct Answer An orbit of the Earth made by a satellite that has the same time period as the rotation of the Earth (i.e. 24 hours) and is in the equatorial plane Kepler's first law - Correct Answer The orbit of a planet is an ellipse with the Sun at one of the two foci Kepler's second law - Correct Answer A line segment connecting a planet to the Sun sweeps out equal areas during equal intervals of time Kepler's third law - Correct Answer The period of a planet orbiting the sun squared is proportional to the mean radius of its orbit cubed. T^2∝r^3 Eccentricity - Correct Answer A measure of the deviation of an elliptical path from a perfect circle Aphelion - Correct Answer Highest point on a heliocentric orbit Perihelion - Correct Answer Lowest point on a heliocentric orbit Gravitational potential - Correct Answer The work done per unit mass to bring an object from infinity to a point in the gravitational field, units Jkg-1 Escape Velocity - Correct Answer The minimum velocity at which an object has just enough energy to leave a specified gravitational field Equilibrium position - Correct Answer The resting position of waves or particles in an oscillation Displacement - Correct Answer Distance from the equilibrium position, as a vector Amplitude - Correct Answer The maximum displacement of an oscillating system Frequency - Correct Answer The number of complete oscillations per unit time (usually measured in Hertz) Period - Correct Answer The time taken for one complete oscillation Phase difference - Correct Answer The number of radians one oscillating system lags behind another (where 2π radians represents a complete cycle, measured in radians) Angular frequency - Correct Answer The number of radians an oscillating system moves through per unit time (where 2π radians represents a complete cycle, measured in radians per second) Simple harmonic motion - Correct Answer Motion where the acceleration of an object is directly proportional to its displacement from an equilibrium point, and directed towards that equilibrium point Isochronous oscillator - Correct Answer Oscillator with a constant time period Free oscillation - Correct Answer An oscillating system not experiencing any external forces Natural frequency - Correct Answer The frequency that a system oscillates at when freely oscillating Forced oscillation - Correct Answer An oscillating system being driven by a periodic external driving force Driving frequency - Correct Answer The frequency of the driving force acting on an oscillating system Resonance - Correct Answer The rapid increase in amplitude observed when the driving frequency is close to the natural frequency of a system Damping - Correct Answer The result of an external force acting on an oscillator which causes its amplitude to decrease Light damping - Correct Answer A gradual decrease in the amplitude of an oscillating system over many oscillations Heavy damping - Correct Answer A rapid decrease in the amplitude of an oscillating system over very few oscillations Astronomical unit - Correct Answer The mean distance from the earth to the sun (1.50×10^11m) Nebula - Correct Answer A cloud of dust and gas (mainly hydrogen), often many hundreds of times larger than our solar system Protostar - Correct Answer A very hot, very dense sphere of condensing dust or gas that is on the way to becoming a star Nuclear fusion - Correct Answer A process in which two smaller nuclei join together to form one larger nucleus Radiation pressure - Correct Answer Pressure from the photons in the core of a star, which acts outwards to counteract the pressure from the gravitational force pulling the matter of the star inwards Main sequence - Correct Answer The main period on an H-R diagram in a star's life, during which it is stable, as the gravitational forces are balanced by the radiation pressure Red giant - Correct Answer An expanding star at the end of its life, with an inert core in which fusion no longer takes place, but in which fusion of lighter elements continues in a shell around the core Red supergiant - Correct Answer A huge star in the last stages of its life before it 'explodes' in a supernova Supernova - Correct Answer The implosion of a red supergiant at the end of its life, which leads to the subsequent ejection of stellar matter into space, leaving an inert remnant core White dwarf - Correct Answer A very dense star formed from the core of a red giant, in which no fusion occurs Electron degeneracy pressure - Correct Answer A quantum-mechanical pressure created by the electrons in the core of a collapsing star due to the Pauli exclusion principle Chandrasekhar limit - Correct Answer The mass of a star's core beneath which the electron degeneracy pressure is sufficient to prevent gravitational collapse, 1.44 solar masses Neutron star - Correct Answer The remnant of a massive star after the star has gone supernova and the core has collapsed under pressure to an extremely high density and is made almost entirely of neutrons Black hole - Correct Answer The remnant of a massive star after the star has gone supernova and the core has collapsed so far that the escape velocity is greater than the speed of light. Therefore nothing can escape. Luminosity - Correct Answer Total power radiated by a star Hertzsprung-Russell diagram - Correct Answer A diagram plots stars on scatter graph of luminosity vs temperature. Where temperature plotted backwards. Energy levels - Correct Answer Discrete amounts of energy that an electron within an atom is permitted to possess. Ground state - Correct Answer The energy level with the most negative value possible for an electron within that particular atom, this is the most stable energy state which the electron can be within the atom Excited - Correct Answer An atom containing an electron or electrons that have absorbed energy and have been boosted into a higher energy level Spectroscopy - Correct Answer A technique that splits white light into different frequencies so that spectral lines can be used to determine the elemental composition of stars and planets Spectral line - Correct Answer A line in an emission line spectrum or absorption line spectrum at a specific wavelength Emission spectra - Correct Answer A set of specific frequencies emitted by excited atoms. Each element produces a unique emission line spectrum due to its unique set of energy levels Continuous spectra - Correct Answer All visible frequencies or wavelengths are present. The atoms of a heated solid metal will produce this type of spectrum Absorption spectra - Correct Answer This type of spectrum has a series of dark spectral lines against the background of a continuous spectrum. The dark lines have exactly the same wavelengths as the bright emission spectral lines of the same gaseous atoms. Diffraction grating - Correct Answer A glass or plastic slide on which as many as 1000 lines per mm are ruled at a spacing that diffracts visible wavelengths of light. Wien's displacement law - Correct Answer States that the wavelength of the maximum intensity is inversely proportional to the temperature of the black body Stefan's law - Correct Answer States that 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 Stefan's constant - Correct Answer The constant of proportionality in Stefan's law. 5.67×10-8Wm-2K-4 Light-year - Correct Answer Distance travelled by light in one year in a vacuum Arcsecond - Correct Answer 1/3600 of a degree Parsec - Correct Answer The distance at which a radius of 1 AU subtends at an angle of one arc second Parallax angle - Correct Answer The angle of the apparent shift in the position of a nearby star as compared with background stars, over six months Blue-shift - Correct Answer The distortion of a wave when the source is moving *closer*, the wavelength contracts Red-shift - Correct Answer The distortion of a wave when the source is moving *away*, the wavelength spreads out Doppler equation - Correct Answer The ratio of change in frequency to frequency is roughly equal to the ratio of recession speed to speed of light Big bang - Correct Answer The theory that at a moment in the pass all the matter in the universe was contained in a singularity, the beginning of space and time, that expanded rapidly outwards. Cosmological principle - Correct Answer The universe is homogeneous and isotropic Homogeneous - Correct Answer Matter is distributed uniformly across universe Isotropic - Correct Answer The universe looks the same in all directions to every observer Hubble's law - Correct Answer The recession speed of distant galaxies is roughly directly proportional to their distance from Earth Hubble's constant - Correct Answer The constant of proportionality in Hubble's Law, equal to 1/ age of the universe Microwave background radiation - Correct Answer The microwave signal of uniform intensity detected from all directions of the sky which fits the profile for a blackbody at temperature 2.7K Dark energy - Correct Answer A hypothetical form of energy which fills all of space, thought to be a reason for the acceleration of the universe's expansion Dark matter - Correct Answer Matter that does not interact with light or the electromagnetic force, but does interact with other forces radio - Correct Answer 10^3 microwave - Correct Answer 10^-2 Infrared - Correct Answer 10^-5 visible - Correct Answer 0.5 x 10^-6 ultraviolet - Correct Answer 10^-8 x ray - Correct Answer 10^-10 gamma ray - Correct Answer 10^-12 Brownian motion - Correct Answer The continuous, random motion of small particles suspended in a fluid, visible under a microscope.