Physical sciences paper 1 definitions Flashcards
normal force
the force or the component of a force which a surface exerts on an object with which it is in contact, and which is perpendicular to the surface.
frictional force
the force that opposes the motion of an object and which
acts parallel to the surface.
Static frictional force
the force that opposes the tendency of motion of a
stationary object relative to a surface.
kinetic frictional force
as the force that opposes the motion of a moving object
relative to a surface.
newton’s first law of motion
A body will remain in its state of rest or motion at
constant velocity unless a non-zero resultant/net force acts on it.
newton’s second law of motion
when a net force is applied to an object of mass, it accelerates in the direction of the net force. the acceleration is directly proportional to the net force and inversely proportional to the mass
newton’s third law of motion
When object A exerts a force on object B, object B exerts a force of equal magnitude in the opposite direction of object A
newton’s universal law of gravitation
Each body in the universe attracts every other body with a force that is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centres.
weight
the gravitational force the Earth exerts on any object on or near its surface.
weightlessness
weightlessness is the sensation experienced when all contact forces are removed i.e no external forces touch ones body
momentum
as the product of an object’s mass and its velocity
linear momentum
A vector quantity with the same direction as the velocity
of the object.
Newton’s second law of motion in terms of momentum
The net (or resultant) force acting on an object is equal to the rate of change of momentum of the object in the direction of the net force.
Impulse
Is the product of the resultant/net force acting on an object and the time the net force acts on the object.
System
A system is a collection of two or more objects that interact with each other
Isolated system
A system on which the resultant/net External force is zero
the principle of conservation of linear momentum
The total linear momentum of an isolated system remains constant (is conserved)
Work- energy theorem
The net work done on an object is equal to the change in the object’s kinetic energy.
Conservative force
Force for which the work done in moving an object between two points independent of the path taken.
Non-Conservative force
Force for which the work done in moving an object between two points depends on the path taken.
Principle of conservation of mechanical energy
The total mechanical energy (sum of gravitational potential energy and kinetic energy) in an isolated system remains constant
power
The rate at which work is done
Gravitational potential energy
The energy an object has because of its position in the gravitational field relative to some reference point.
Doppler Effect
as the change in frequency (or pitch) of the sound detected by a listener, because the sound source and the listener have different velocities relative to the medium of sound propagation.
Coulomb’s law
The magnitude of the electrostatic force exerted by one point charge (Q1) on another point charge (Q2) is directly proportional to the product of the magnitudes of the charges and inversely proportional to the square of the
distance (r) between them:
electric field
as a region of space in which an electric charge experiences a force. The direction of the electric field at a point is the direction that a positive test charge would move if placed at that point.
Electric field strength at a point
The electric field strength at this point is the electrostatic force experienced per unit positive charge placed at that point.
Ohm’s Law
the potential difference across a conductor is directly proportional to the current in the conductor at constant temperature.
power
is the rate at which work is done or energy is transferred.
emf
the maximum energy supplied by a battery per unit charge passing through it
The rms potential difference
is the AC potential difference which dissipates/produces
the same amount of energy as an equivalent DC potential difference.
The rms current
is the alternating current which dissipates/produces the same amount
of energy as an equivalent direct current (DC).
photoelectric effect
as the process whereby electrons are ejected from a
metal surface when light of suitable frequency is incident on that surface.
threshold frequency, fo,
as the minimum frequency of light needed to emit electrons from a certain metal surface.
work function, Wo,
as the minimum energy that an electron in the metal needs to
be emitted from the metal surface.
