Definitions Flashcards
Work
the product of the force and displacement (of its point of application) in the direction of the force OR when an object is moved over a distance by an external force applied in the direction of its displacement
Electric field strength
The electrostatic force per unit positive charge acting on a stationary point charge at that point.
Scalar
A scalar is a quantity which only has a magnitude (size)
Vector
It is a quantity that has both direction and magnitude
Random error
Random errors cause unpredictable fluctuations in an instrument’s readings as a result of uncontrollable factors,
Systematic error
Systematic errors arise from the use of faulty instruments used or from flaws in the experimental method
precision
this is how close the measured values are to each other
accuracy
this is how close a measured value is to the true value
Distance
the total length between two points
Speed
the total distance travelled per unit of time
Displacement
the distance of an object from a fixed point in a specified direction
Velocity
the rate of change of displacement of an object
Acceleration
the rate of change of velocity of an object
mass
Mass is the measure of the amount of matter in an object
Weight
is the effect of a gravitational field on a mass OR product of mass and acceleration due to gravity or the gravitational field strength.
newton’s first law
A body will remain at rest or move with constant velocity unless acted on by a resultant force
newton’s second law
A resultant force acting on a body will cause a change in momentum in the direction of the force. The rate of change in momentum is proportional to the magnitude of the force
newton’s third law
If body A exerts a force on body B, then body B will exert a force on body A of equal magnitude but in the opposite direction
Momentum
Product of mass and velocity
Force
the rate of change of momentum on a body
Drag force
Drag forces are forces acting the opposite direction to an object moving through a fluid .eg. air resistance , friction
The principle of conservation of momentum
The total momentum of a system remains constant provided no external force acts on it OR the total momentum before the collision = the total momentum after the collision
External forces
forces that act on a structure from outside
Internal Forces
forces exchanged by the particles in the system
Closed system
a system with no external forces
Elastic collisions
where objects colliding do not stick together ,then move in opposite directions and the kinetic energy is conserved
Inelastic collision
where objects collide and stick together after the collision and kinetic energy is not conserved
Centre of Gravity
the point at which the weight of the object may be considered to act
Centre of mass
the point at which the mass of the object may be considered to act
Moment
The turning effect of the force OR the product of force and perpendicular distance from the pivot in a particular direction
Principle of Moments
For a system to be in equilibrium, the sum of clockwise moments about a point must be equal to the sum of the anticlockwise moments (about the same point)
Couple
A couple is a pair of forces that acts to produce rotation only
Torque
The moment of the couple
Density
mass per unit volume of an object
Pressure
force per unit area
Hydrostatic Pressure
pressure that is exerted by a fluid at equilibrium at a given point within the fluid, due to the force of gravity
Upthrust
force which pushes upwards on an object submerged in a fluid i.e. liquids and gases
Archimedes Principle
an object submerged in a fluid at rest has an upward buoyancy force (upthrust) equal to the weight of the fluid displaced by the object
Principle of Conservation of Energy
Energy cannot be created or destroyed, it can only change from one form to another
Efficiency
the ratio of the useful energy output from the system to the total energy input
Power
rate at which it transfers energy
G.P.E
Gravitational potential energy is energy stored in a mass due to its position in a gravitational field
Kinetic Energy
energy an object has due to its motion (or velocity)
Hooke’s Law
its extension is directly proportional to the applied force (load)
Tensile stress
applied force per unit cross sectional area of a material
Strain
extension per unit length
Young Modulus
The Young modulus is the measure of the ability of a material to withstand changes in length with an added load ie. how stiff a material is
Elastic Deformation
when the load is removed, the object will return to its original shape
Plastic Deformation
when the load is removed, the object will not return to its original shape or length. This is beyond the elastic limit
Elastic Limit
the point beyond which the object does not return to its original length when the load is removed
Elastic potential energy
energy stored within a material (e.g. in a spring) when it is stretched or compressed
Transverse Waves
The oscillations/vibrations can be perpendicular or parallel to the direction of wave travel:
When they are perpendicular, they are transverse waves.A transverse wave is one where the particles oscillate perpendicular to the direction of the wave travel (and energy transfer)
Longitudinal Waves
When they are parallel, they are longitudinal waves.A longitudinal wave is one where the particles oscillate parallel to the direction of the wave travel (and energy transfer)
Displacement
Displacement (x) of a wave is the distance from its equilibrium position.
Amplitude
Amplitude (A) is the maximum displacement of a particle in the wave from its equilibrium position
Wavelength
Wavelength (λ) is the distance between points on successive oscillations of the wave that are in phase
Period
Period (T) or time period, is the time taken for one complete oscillation or cycle of the wave.
Frequency
Frequency (f) is the number of complete oscillations per unit time.
Phase difference
The phase difference tells us how much a point or a wave is in front or behind another
Progressive Waves
Waves that transfer energy are known as progressive waves
Stationary Waves
Waves that do not transfer energy are known as stationary wave
Intensity
The amount of energy passing (power) through a unit area per unit time
Spherical Waves
A spherical wave is a wave from a point source which spreads out equally in all directions
Doppler Effect
This frequency change due to the relative motion between a source of sound or light and an observer
Principle of Superposition
The principle of superposition states that when two or more waves with the same frequency travelling in opposite directions overlap, the resultant displacement is the sum of displacements of each wave
Antinodes
Antinodes are where the vibrations are at their maximum amplitude
Nodes
Nodes are where there is no vibration
Diffraction
Diffraction is the spreading out of waves when they pass an obstruction
Interference
sum of the displacement of each wave
Current
the flow of charge carriers
Conventional current
flow of positive charge from the positive terminal of a cell to the negative terminal
Potential Difference
energy transferred per unit charge flowing from one point to another
Resistance
opposition to current
Ohm’s Law
Ohm’s law states that for a conductor at a constant temperature, the current through it is proportional to the potential difference across it
Resistivity
Resistivity is a property that describes the extent to which a material opposes the flow of electric current through it
e.m.f
the potential difference across the cell when no current is flowing OR the amount of chemical energy converted to electrical energy per coulomb of charge (C) when charge passes through a power supply
Kirchoff’s First Law
The sum of the currents entering a junction always equal the sum of the currents out of the junction
Kirchoff’s Second Law
The sum of the e.m.f’s in a closed circuit equals the sum of the potential differences
Quark
Quarks are fundamental particles that make up other subatomic particles
