Physics Definitions Flashcards
Resultant vector
the vector sum of two or more vectors, i.e. a single vector having the same effect as two or more vectors together.
normal force, N
the force or the component of a force which a surface exerts
on an object in contact with it, and which is perpendicular to the surface.
frictional force, f
the force that opposes the motion of an object in contact with a surface and which acts parallel to the surface.
static friction
the force that opposes the tendency of motion of a stationary object relative to a surface.
kinetic friction
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 resultant/net force acts on an object, the object will accelerate in the direction of the force at an acceleration directly proportional to the force and inversely proportional to the mass of the object.
Newton’s third law of motion:
When object A exerts a force on object B, object B
SIMULTANEOUSLY exerts an oppositely directed force of equal magnitude on object A.
Newton’s law of universal gravitation:
Each particle in the universe attracts every other particle with a gravitational 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, in newton (N), exerted by the Earth on an object.
mass
the amount of matter in a body measured in kilogram (kg).
weightlessness
the sensation experienced when all contact forces are
removed
wave front
an imaginary line joining points on a wave that are in phase.
Huygens’ principle:
Every point of a wave front serves as a point source of spherical, secondary waves that move forward with the same speed as the wave.
diffraction
the ability of a wave to spread out in wave fronts as the wave passes through a small aperture or around a sharp edge.
Coulomb’s law:
The magnitude of the electrostatic force exerted by two point charges (Q1 and Q2) on each other 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
a region in 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.
Ohm’s law
The potential difference across a conductor is directly
proportional to the current in the conductor at constant temperature.
power
rate at which work is done or energy is transferred.
kilowatt-hour (kWh)
to the use of 1 kilowatt of electricity for
1 hour.
Faraday’s law of electromagnetic induction:
The magnitude of the induced emf across the ends of a conductor is directly proportional to the rate of change in the magnetic flux linkage with the conductor.
Electric field strength at a point
The electrostatic force experienced per unit positive charge placed at that point.
