Year 12 definitions random order Flashcards
Newton’s first law
A body will remain at rest or continue to move in a straight line at a constant velocity unless an external force acts on it.
Brittle
A brittle material will break with little or no plastic deformation.
A closed system.
A closed system is any system in which all the energy transfers are accounted for.
Energy or matter cannot enter or leave a closed system.
Ductile
A ductile material can be drawn into wires and will show plastic deformation under tensile stress before breaking.
Hard
A hard material will resist plastic deformation by surface indentation or scratching.
Kilowatt-hour
A kilowatt-hour is the energy transferred by 100 W in 3600 seconds. It si therefore equal to 3,600,000 J.
Malleable
A malleable material can be hammered or beaten into flat sheets and will show extensive plastic deformation when subject to compressive forces.
Photon
A photon is a quantum associated with electromagnetic radiation.
Polymer
A polymer is a material made of long chains of molecules.
Potential divider
A potential divider circuit uses two resistors in series to split or divide the voltage of the supply in a chosen ratio so that a chosen voltage can be supplied to another device or circuit.
Progressive wave
A progressive wave is a wave that tranfers energy away from a source.
Quantum
A quantum is a small discrete unit of energy.
Scalar
A scalar quantity is one which has magnitude but not direction.
Systematic error
A systematic error is one that doesn’t happen by chance, but as a result of an inaccuracy in the apparatus or its use by the person using it. This type of error tends to shift all the results in the same direction.
Vector
A vector quantity is one which has both magnitude and direction.
Vector triangle
A vector triangle is a type of scale diagram with two vectors drawn tip-to-tail, to show how they can be added together.
Zero error
A zero error is a type of systematic error caused by an instrument not being properly calibrated or adjusted. It then gives a non-zero value when the value should be zero.
Accuracy
Accuracy is a measure of the closeness of agreement between an individual test result and the true value. If a test result is accurate, it is in close agreement with the true value.
Anomalous value
An anomalous value in a set of results is one that does not fit the overall trend in the data. it is therefore discounted from any analysis.
Elastic collision
An elastic collision is one in which both the momentum and kinetic energy are conserved. No energy is transferred to other forms.
Inelastic collision
An inelastic collision is one in which the momentum is conserved but some of the kinetic energy is transferred to other forms.
Fiducial mark
An object placed in the field of view for an observer to use as a reference point.
Anti-nodes on a stationary wave
Anti-nodes on a stationary wave are points where displacement is a maximum.
Archimedes’ principle
Archimedes’ principle states that the upward buoyant force (upthrust) exerted on an object immersed in a fluid is equal to the weight of the fluid displaced.
Diffraction
Diffraction is the spreading out of a wave after passing around an obstacle or through a gap.
Elasticity
Elasticity is the property of a body to resume its original shape or size once ethe deforming force or stress has been removed.
Error
Error (of measurement) is the difference between an individual measurement and the true value (or accepted reference value) of the quantity being measured.
Hooke’s Law
Hooke’s Law states that the extension of an object is proprtional to the force that causes it, provided that the elastic limit is not exceeded.
Newton’s third law
If object A exerts a force on object B, then object B will exert an equal and opposite force on object A.
Impulse
Impulse is the product of force and the the time for which the force acts.
Plane polarisation
In a plane polarised wave the oscillations of the field and the direction of travel are confined to a single plane.
Interference
Interference is the addidtion of two or more waves (superposition) that causes a new wave pattern.
Kirchoff’s first law
Kirchoff’s first law states that the sum of currents entering a junction is equal to the sum of currents leaving the junction.
Kirchoff’s second law
Kirchoff’s second law states that in any close loop, the sum of the e.m.f. is equal to the sum of the products of the current and the resistance.
Nodes on a stationary wave
Nodes on a stationary wave are points at which there is no displacement of the particles at any time.
Equilibrium
Objects are in equilibrium when all the forces acting on them in the same plane (coplanar forces) are balanced - there is zero net or resultant force.
Ohm’s Law
Ohm’s law states that the current through a conductor is directly proportional to the potential difference across it, provided the temperature remains constant.
One Newton
One Newton is the force needed to give a mass of 1 kg an acceleration of 1 metre per second squared.
Path difference
Path difference is the difference in distance (measured in m or numbers of wavelengths) travelled by two waves arriving at the same point.
Percentage difference
Percentage difference is the difference between two values divided by the mean and expressed as a percentage.
Percentage uncertainty
Percentage uncertainty is the uncertainty divided by the measured value and expressed as a percentage.
Phase difference
Phase difference is the difference in phases, measured in radians, of two waves of the same frequency.
Precision
Precision is the closeness of agreement between independent measurements obtained under the same conditions. It depends only on the distribution of random errors (i.e. the spread of measurements) and does not relate to the true value.
Random error
Random errors give values that are scattered randomly above and below the true value when the measurement is repeated. Taking a mean of repeated values obtains a better result.
Repeatability
Repeatability is the precision obtained when measurement results are produced over a short timescale by one person (or the same group) using the same equipment in the same place.
Reproducibility
Reproducibility is the precision obtained when measurement results are produced over a wider timescale by different people using equivalent equipment in different (but equivalent) places.
Resolution
Resolution is the smallest change in the quantity being measured that can be detected by an instrument.
Stiffness
Stiffness is the ability of a material to resist a tensile force.
Strain
Strain is extension per unit length. It has units and is therefore dimensionless.
Stress
Stress is force per unit cross-sectional area. It has unit Nm-2 or Pa and the symbol σ
Centre of mass
The centre of mass of an object is the single point at which all of the mass of the object can be assumed to be situated.
The components of a vector
The components of a vector are the parts of a vector in two perpendicular directions.
Density
The density of an object is its mass per unit volume.
Electromotive force (e.m.f.)
The e.m.f. of a supply is the energy gained per unit charge by charges passing through the supply, when a form of energy is trasnferred to electrical energy carried by the charges. It is measure in volts or joules per coulomb.
Electronvolt
The electronvolt is the kinetic energy gained by an electron when it is accelerated through a potential difference of 1 V.
Intensity
The intensity of a progressive wave is the rate at which energy is transferred perpendicular to the direction of wave travel.
I = P/A in Wm-2
The moment of a force
The moment of a force (or turning moment) is the product of the force and the perpendicular distance of its line of action from the pivot or axis.
Potential difference (p.d.)
The p.d. across a componenet is the energy transferred per unit charge by the charges passing through the component. It is measured in volts or joules per coulomb.
The principle of conservation of energy
The principle of conservation of energy states that the total energy of a closed system remains constant. Energy cannot be created or destroyed, it can only be transferred from one form to another.
The principle of moments
The principle of moments states that for an object to be in rotational equilibrium, the sum of the clockwise moments must equal the sum of the anti-clockwise moments.
The principle of superposition
The principle of superposition states that when two or more waves of the same type meet, the resultant displacement of the wave can be found by adding the displacement of the individual waves.
Newton’s second law
The resultant force on an object is proportional to the rate of change of momentum of the object, and the momentum change takes place in the direction of the force.
Terminal p.d.
The terminal p.d. is the p.d. recorded across the terminals of a cell. The difference between the e.m.f. and the p.d. when charge flows is called the ‘lost volts’.
Threshold frequency
The threshold frequency is the lowest frequency of radiation that will result in the emission of electrons from a particular metal surface.
Resultant vector
The vector sum of two or more vectors.
Work done
The work done, or energy transferred, is the product of the force and the distance moved by the force in the direction of movement.
Work function
The work function of a metal is the minimum energy that will result in the emission of an electron from a particular metal surface.
Young modulus
The Young modulus is the ratio of stress/strain for a given material.
Torque
Torque is the moment of a couple. The torque of a couple is the product of one of the forces and the perpendicular distance between them.
Ultimate tensile strength
Ultimate tensile strength is the maximum stress a material can withstsnad while being pulled or stretched, before it fails or breaks.
Uncertainty
Uncertainty is an estimate attached to a measurement which characterises the range of values within which the true value is asserted to lie. This is normally expressed as a range of values such as 44.0 ± 0.4.
Valididty
Validity can apply to an individual measurement or a whole investigation. A measurement is valid if it measures what it is supposed to be measuring. An investigative procedure is valid if it is suitable to answer the question being asked.
