ALL DEFINITIONS PAPER 2 Flashcards
Scalar quantity:
A quantity that has magnitude only (e.g., distance, speed).
Vector quantity:
A quantity that has both magnitude and an associated direction (e.g.,
displacement, velocity, force).
Weight
: The force acting on an object due to gravity.
Gravitational field strength (g):
The force per unit mass due to gravity, measured in newtons
per kilogram (N/kg).
Centre of mass:
The point at which the weight of an object may be considered to act
Resultant force:
A single force that has the same effect as all the original forces acting together on an object.
Work done:
When a force causes an object to move through a distance, energy is transferred, and the work done is equal to the force multiplied by the distance moved in the direction of
the force
Elastic deformation:
: When an object returns to its original shape after a deforming force is
removed.
Inelastic deformation:
: When an object does not return to its original shape after a deforming
force is removed
Limit of proportionality
The point beyond which Hooke’s law (force is directly proportional to
extension) is no longer obeyed for a spring or other elastic object
Fluid
: A substance that can flow, either a liquid or a gas
Pressure
The force per unit area.
Atmospheric pressure
The pressure created by air molecules colliding with a surface
Speed
The rate of change of distance.
Velocity
The rate of change of displacement.
Acceleration
The rate of change of velocity
Deceleration
Negative acceleration
Terminal velocity
The constant velocity reached by an object when the resistive forces (e.g. air resistance) equal the accelerating force (e.g., weight)
Newton’s First Law:
: An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force (resultant
force is zero).
Inertia
The tendency of an object to resist a change in its state of motion
Newton’s Second Law
The acceleration of an object is directly proportional to the resultant
force acting on the object and inversely proportional to its mass
Inertial mass:
A measure of how difficult it is to change the velocity of an object, defined as the
ratio of force over acceleration.
Newton’s Third Law:
: For every action, there is an equal and opposite reaction
Stopping distance:
The sum of the thinking distance and the braking distance
Thinking distance
The distance a vehicle travels during the driver’s reaction time.
Reaction time:
The time it takes for a driver to react to a hazard.
Braking distance:
The distance a vehicle travels under the braking force.
Conservation of momentum
In a closed system, the total momentum before an event is equal to the total momentum after the event
Wave
A transfer of energy from one place to another without the transfer of matter
Transverse wave:
: A wave where the oscillations are perpendicular to the direction of energy transfer (e.g., water ripples, electromagnetic waves).
Longitudinal wave
: A wave where the oscillations are parallel to the direction of energy
transfer (e.g., sound waves).
Amplitude
The maximum displacement of a point on a wave away from its undisturbed
position
Wavelength (λ)
The distance from a point on one wave to the equivalent point on the adjacent wave.
Frequency (f)
The number of waves passing a point each unit of time
Period (T)
The time taken for one complete wave to pass a point
Refraction:
The change in direction of a wave as it passes from one medium to another due to a change in speed.
Absorption
: When a wave transfers its energy to the material it is passing through.
Transmission
When a wave passes through a material.
Focal length
The distance from a lens to its principal focus.
Magnification
The ratio of the image height to the object height
Specular reflection
: Reflection from a smooth surface in a single direction.
Diffuse reflection
Reflection from a rough surface that causes scattering
Black Body:
An object that absorbs all the electromagnetic radiation that land upon its surface.
Magnetic pole (north and south)
The regions of a magnet where the magnetic field is
strongest
Magnetic field:
The region around a magnet where a force acts on another magnet or on a
magnetic material.
Solenoid
A coil of wire that creates a magnetic field when an electric current flows through it.
Electromagnet
A solenoid with an iron core, whose magnetic field strength can be increased by increasing the current or the number of turns in the coil.
Motor effect
: The force on a current-carrying conductor in a magnetic field.
Magnetic flux density (B):
A measure of the strength of a magnetic field.
Generator effect (electromagnetic induction):
The induction of a potential difference (and
current if the circuit is complete) across a conductor moving relative to a magnetic field or
when there is a change in the magnetic field around a conductor.
Alternator
A generator that produces alternating current (ac)
Dynamo
o: A generator that produces direct current (dc).
Transformer
A device that uses electromagnetic induction to change the potential difference
of an alternating current supply.
Planet
A celestial body orbiting a star
moon
A natural satellite orbiting a planet.
Artificial satellite:
: A man-made object that orbits a planet
Red-shift:
The observed increase in the wavelength of light from distant galaxies, indicating that they are moving away from us.
Big Bang theory:
The prevailing cosmological model for the universe that describes it
expanding from an initial state of extremely high density and high temperature
Dark mass:
: Non-luminous matter whose presence can be inferred from its gravitational effects
on visible matter
Dark energy:
A hypothetical form of energy that is thought to be responsible for the
accelerating expansion of the universe
