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