A2 definitions Flashcards
State Newton’s 1st law of motion.
An object will move at constant velocity unless acted upon by an unbalanced force.
State Newton’s 2nd Law of Motion.
The unbalanced force on an object is given by the rate of change of momentum.
State Newton’s 3rd Law of Motion.
For every force there is an equal but opposite force.
Define Linear Momentum.
The product of the mass and velocity of an object.
The net or ‘resultant’ force on a body is equal to…
The rate of change of momentum.
Define ‘impulse’
The change of momentum of an object.
Ft, where F is the force on an object t is the time for which it acts
State the law of conservation of linear momentum.
For an isolated system, the total linear momentum in any direction is a constant.
What is a ‘perfectly elastic’ collision?
A collision where kinetic energy is conserved.
What is an ‘inelastic’ collision?
A collision where kinetic energy is NOT conserved.
What is a radian?
A unit of angle where one full circle (360°) is equivalent to 2 radians.
Define ‘gravitational field strength’
The gravitational force per unit mass.
The gravitational flux per unit perpendicular area.
Define ‘gravitational potential’
The energy needed to bring a unit point mass from infinity to a given location.
State Newton’s Law of Universal Gravitation.
The force (F) between two point masses (M1 and M2), a distance d apart is given by:
Define ‘electric field strength’
The electric force per unit positive charge.
The electric flux per unit perpendicular area.
Define ‘electric potential’
The energy needed to bring a unit point charge from infinity to a given location.
What is a geostationary orbit?
The orbit of a satellite such that it is directly above a fixed point on the Earth.
Define ‘internal energy’ of a system
The sum of the total kinetic energy and potential energy of a system.
Pressure
The force per unit area
Absolute zero
The temperature at which the internal energy of a system is a minimum. Equal to -273C or 0 K
State Boyle’s Law.
For a system at constant temperature, the product of pressure and volume is a constant.
PV = constant.
Define the mole.
The amount of a substance such that there are 6.02 x 10²³ basic particle present.
What is Avogadro’s Constant?
6.02 x 10²³, the number of particles in a system when there is 1 mole present.
Define ‘specific heat capacity’
The heat energy needed to raise 1kg of a substance by 1K.
Define ‘latent heat of fusion’
The heat energy needed to change 1kg of a solid into a liquid.
Define ‘latent heat of caporisation.’
The heat energy needed to change 1kg of a liquid into a gas.
Define ‘the magnetic flux’ (e.g. through a loop)
BA, where A is the area of the loop and B is the magnetic flux density perpendicular to the plane in which the loop lies.
Define ‘magnetic flux density’.
The magnetic flux density, B, is defined as F/IL, where F is the force on a conductor, L is the length of the conductor in the magnetic field, and I is the current in the conductor.
Define the Tesla.
The magnetic field strength required to produce a 1N force on a wire of 1m length, with a 1A current flowing.
Define the Weber.
The number of flux lines through a 1m² area in a field of strength 1T
Define ‘magnetic flux linkage’.
The product of the magnetic flux and the number of turns in a coil.
State Lenz’s Law
The induced EMF is in such a direction as to oppose the change producing it.
State Faraday’s Law.
Induced EMF = minus the rate of change of magnetic flux linkage
Define ‘capacitance.’
The stored charge in a capacitor per unit voltage across the plates.
Define the capacitive ‘time constant’
Equals RC, where C is the capacitance of a capacitor and R is the resistance through which it is charging or discharging.
Also: the time taken for a capacitor to reduce its charge to 1/e (=approximately 37%) of its maximum value.
Define the Farad.
The capacitance of a capacitor which stores a charge of 1C when a p.d. of 1V is applied across the plates.
Define ‘displacement’ (in the context of SHM)
The distance moved, in a particular direction, from the rest point by an oscillating particle.
State what is meant by the ‘amplitude’ of an object executing SHM.
The maximum distance the object moves from the rest point.
Define the ‘period’ of an oscillation.
The time taken for one complete cycle to occur.
Define the ‘frequency’ of an oscillation.
The number of cycles in 1 second.
Define ‘phase difference’.
The amount by which two waves are out of step with each other. It is measured in degrees or radians.
