Revision - Modelling Physics definitions Flashcards
What is displacement?
Displacement is defined as the distance travelled in a particular direction.
What is velocity?
Velocity is defined as the rate of change of displacement.
What is a scalar quantity?
A scalar quantity only has magnitude.
What is a vector quantity?
A vector quantity has both magnitude and direction.
What is acceleration?
Acceleration is defined as the rate of change of velocity.
What is instantaneous speed?
The instantaneous speed is the speed of an object at a particular moment in time.
(gradient of tangent to distance time graph)
What is average speed?
Average speed is the rate of change of distance.
What is terminal velocity?
The terminal velocity is the velocity of an object when resultant force is zero.
What is reaction time?
The reaction time is the time between the driver seeing the obstacle and actually applying the brakes.
What is thinking distance?
Thinking distance is the distance the car travels between the driver seeing the obstacle and actually applying the brakes.
What is braking distance?
Braking distance is the distance the car travels between the driver applying the brakes and the vehicle coming to rest.
What is stopping distance?
Stopping distance = thinking distance + braking distance.
What is a Newton?
The Newton is defined as the force required to give a mass of 1kg an acceleration of 1ms-2 in the direction of the force.
What is tension?
Tension is the force transmitted through a taut string or cable.
What is normal contact force?
Normal contact force is the force which acts perpendicular to the surface at the point of contact with another object.
What is upthrust?
Upthrust is the upward force that acts on a body fully or partially submerged in a liquid or gas.
What is friction?
Friction is the force which acts to oppose motion along a surface.
What is the moment of a force about a point?
The moment of a force is:
force x perpendicular distance from the line of action of the force to the pivot.
What is a couple?
A couple is defined as a pair of parallel forces of equal magnitude acting in the opposite direction to each other.
What is the torque of a couple?
The torque of a couple is defined as: one of the forces in the couple x the perpendicular distance between the two forces.
What does the principle of moments state?
The principle of moments states: for any object in equilibrium, the sum of the clockwise moments = sum of the anticlockwise moments about a pivot.
What is the centre of gravity?
The centre of gravity of an object is the point where all the weight is considered to act.
When is an object in equilibrium?
An object is in equilibrium if resultant force equals zero and resultant moment is zero.
What is density?
Density is defined as the mass per unit volume.
What is pressure?
Pressure is defined as the normal force per unit cross sectional area.
What does Archimedes Principle state?
Archimedes Principle states the upthrust exerted on a body, whether fully or partially submerged, is equal to the weight of the fluid that the body displaces.
What is work done?
Work done is defined as the force x the displacement moved in the direction of the force.
What is a joule?
A joule is defined as the work done (or energy transferred) when a force of 1N moves a distance of 1m in the direction of the force.
What is the principle of conservation of energy?
The principle of conservation of energy states that in a closed system, energy is neither created nor destroyed but is simply changed from one form to another.
What is power?
Power is the rate of work done.
What is a watt?
A watt is defined as a transfer of energy of 1 joule per second.
What is efficiency?
Efficiency is defined as the ratio between the useful work done in a process to the total energy taken into the system.
What is extension or compression?
Extension or compression is the difference between the new length with a force applied and the original length.
What does Hooke’s Law state?
Hooke’s Law states that force is proportional to extension below the elastic limit.
What is the force constant or spring constant?
The force constant or spring constant is the force per unit extension or compression.
What is stress?
Stress is defined as the force applied per unit cross sectional area.
What is strain?
Strain is defined as the extension per unit original length.
What is ultimate tensile strength?
Ultimate tensile strength is the maximum stress that a material can withstand before it breaks.
What is Young’s Modulus?
Young’s Modulus is the ratio of stress to strain.
What is elastic deformation?
Elastic deformation is a change in the shape of an object where the material returns to its original length when the force is removed.
What is plastic deformation?
Plastic deformation is a change in the shape of an object where the material does not return to its original length when the force is removed.
What is the elastic limit?
The elastic limit is the point beyond which force is no longer proportional to extension (or stress no longer proportional to strain).
What does Newton’s first law state?
Newton’s first law states that a resultant force is necessary to change a state of rest or of uniform motion in a straight line of a body.
What does Newton’s second law state?
Newton’s second law states that the rate of change of momentum of an object is directly proportional to the net force acting on it.
What does Newton’s third law state?
Newton’s third law states that when body A exerts a force on body B, then body B exerts a force on body A that is equal, opposite in direction and of the same type.
What is linear momentum?
Linear momentum is the product of mass and velocity. Momentum is a vector quantity.
What is the net force on a body?
Net force on a body is equal to the rate of change of momentum.
What is impulse?
The impulse of a force is the force multiplied by the time that the force is applied for.
What does the principle of conservation of momentum state?
The principle of conservation of momentum states that, in any direction, in the absence of external forces, the total momentum of a system remains constant.
What is a perfectly elastic collision?
A perfectly elastic collision is one where total momentum and total kinetic energy of the system are conserved.
What is an inelastic collision?
An inelastic collision is one where total momentum is conserved but total kinetic energy of the system is not.
What is thermal equilibrium?
In thermal equilibrium, there is no net flow of thermal energy between the objects.
What is the absolute scale of temperature?
The absolute scale of temperature does not depend on a property of a substance. It starts from absolute zero.
What experiment demonstrates Brownian motion?
Observing the motion of smoke particles as air particles collide with them.
What is internal energy?
Internal Energy is the sum of the random distributions of kinetic and potential energies of all the molecules in the body.
What is specific heat capacity?
Specific heat capacity is the quantity of thermal energy required to raise the temperature of a unit mass of a substance by a unit temperature rise.
What is latent heat of fusion?
Latent heat of fusion is the quantity of energy (per unit mass) required to change it at constant temperature from a solid to a liquid.
What is latent heat of vaporisation?
Latent heat of vaporisation is the quantity of energy (per unit mass) required to change it at constant temperature from a liquid to a gas.
What are the assumptions of the kinetic theory of gases?
The gas contains a large number of molecules in rapid, random motion. Collisions are elastic and negligible in time compared to the time between collisions.
What is a mole?
A mole is an amount of a substance containing 6.02 x 10^23 (Avogadro constant) particles.
What does Boyle’s law state?
Boyle’s law states that the volume of a fixed mass of gas is inversely proportional to the pressure exerted on it, provided the temperature is kept constant.
What is root mean square speed?
Root mean square speed is the root of the mean of the squared velocities of all the particles in a gas.
What is mean square speed?
Mean square speed is the mean of the squared velocities of all the particles in a gas.
What is a radian?
A radian is the angle subtended at the centre of a circle by an arc of length equal to the circle’s radius.
What is centripetal acceleration?
Centripetal acceleration of an object travelling in a circle of radius r with constant speed v is equal to the speed squared divided by the radius.
What is centripetal force?
Centripetal force is the resultant force on an object acting towards the centre of the circle causing the object to move in a circle.
What is the period T of an object describing a circle?
The period T of an object describing a circle is the time taken to complete one revolution.
What is displacement in SHM?
In SHM, displacement is the distance moved by an object from its mean (or rest) position.
What is the amplitude of an oscillation?
The amplitude of an oscillation is the maximum displacement.
What is the period of an oscillation?
The period of an oscillation is the time for one complete pattern of oscillation to take place at any point.
What is the frequency of an oscillation?
The frequency of an oscillation is the number of oscillations per unit time at any point.
What is angular frequency?
The angular frequency of an oscillation is 2π multiplied by the frequency and describes the angle moved in radians per unit time.
What is phase difference?
The phase difference is the angle in radians between two oscillations.
What characterizes an object in simple harmonic motion?
An object in simple harmonic motion has acceleration proportional to displacement and accelerates in the opposite direction to displacement.
What is resonance?
Resonance is the build up of the amplitude of an oscillation when the driving frequency matches the natural frequency.
What are forced oscillations?
Forced oscillations occur when a driving force acts on the object in order to keep it oscillating.
What are free oscillations?
Free oscillations occur when an object oscillates without a driving frequency.
What is gravitational field strength?
Gravitational field strength at any point is the force acting per unit mass at that point.
What does Newton’s law of gravitation state?
Newton’s law of gravitation states that the gravitational force of attraction between two bodies is directly proportional to the product of their masses and inversely proportional to the square of the distance between them.
What is Kepler’s first law?
Kepler’s first law states that the orbit of a planet is an ellipse with the Sun at one of the two foci.
What is Kepler’s second law?
Kepler’s second law states that a line segment connecting a planet to the Sun sweeps out equal areas during equal intervals of time.
What is Kepler’s third law?
Kepler’s third law states that the period of a planet squared is proportional to the mean radius of its orbit cubed.
What is a geostationary orbit?
A geostationary orbit is the orbit of the Earth made by a satellite that has the same time period as the rotation of the Earth (24 hours).
What is gravitational potential?
Gravitational Potential is the work done in bringing a unit mass from infinity to the point.
What is gravitational potential energy?
Gravitational Potential Energy is the capacity for doing work as a result of an object’s position in a gravitational field.
What is escape velocity?
Escape velocity is the minimum velocity at which an object has just enough energy to leave a gravitational field.
What is an astronomical unit?
One astronomical unit is the average distance between the Sun and the Earth: 1 AU = 1.496 × 10^11 m.
What is a parsec?
1 parsec is defined as the distance to a star which subtends an angle of 1 arc second to the line from the centre of the Earth to the centre of the Sun.
What is a light year?
One light year is the distance light travels through space in 1 year and equals 9.5 × 10^15 m.
What does Hubble’s law state?
Hubble’s law states that the speed of recession of a galaxy is proportional to the distance to that galaxy.
What is the cosmological principle?
The cosmological principle states that, on a large scale, the universe is homogenous and isotropic.
What does homogenous mean in terms of the universe?
Homogenous means that the universe has a uniform density on a large scale.
What does isotropic mean in terms of the universe?
Isotropic means the universe looks the same in all directions on a large scale.
What is the Doppler effect?
The Doppler effect is the change in wavelength and frequency of the wave due to the relative motion of the source and detector.
What is electron degeneracy pressure?
Electron degeneracy pressure is a quantum mechanical pressure created by electrons in the core of a collapsing star due to the Pauli exclusion principle.
What is the Chandrasekhar limit?
The Chandrasekhar limit is the mass of a star’s core beneath which the electron degeneracy pressure is sufficient to prevent gravitational collapse (1.44 x solar mass).
What is a continuous spectrum?
A continuous spectrum is a spectrum in which all wavelengths/frequencies are present.
What is an emission line spectrum?
An emission line spectrum is a set of specific frequencies of EM radiation emitted by excited atoms as their electrons make transitions from higher to lower energy states.
What is an absorption line spectrum?
An absorption line spectrum is a set of specific frequencies of EM radiation visible as dark lines in an otherwise continuous spectrum.
What does Wien’s displacement law state?
Wien’s displacement law states that the peak wavelength λmax at which the intensity of radiation from a black body is a maximum is inversely proportional to the absolute temperature T of the black body.
What is the luminosity of a star?
The luminosity of a star is the total radiant power output of a star.
What is dark energy?
Dark energy is a hypothetical form of energy that would fill all of space and would explain the accelerating expansion of the universe.
What is dark matter?
Dark matter is a hypothetical form of matter spread throughout the galaxy that neither emits nor absorbs light.
