gr 12 physics all definitions

define a vector

A physical quantity that has both direction and magnitude

Define scalar

A physical quantity that has only magnitude

Define a resultant vector

the single vector that has the same effect as the original vectors acting together

Define distance

Length of path traveled

Define displacement

Change in position

Define velocity

The rate of change of displacement

Define speed

The rate of change of distance

define a projectile

An object that has been given an initial velocity and then moves under the influence of gravitational force only

Define free fall

The motion during which the only force acting on the object is the gravitational force

Define weight

The gravitational force the earth exerts on any object on or near its surface

Define normal force

Th perpendicular force exerted by a surface on an object in contact with it

Define frictional force

The force that opposes the motion of the object

What is maximum static friction

the force opposing the motion of an object just before it is about to start moving

Define inertia

The property of an object that causes it to resist a change in its state of rest or uniform motion

State Newton’s first law

An object continues in its state of uniform velocity unless acted upon by a net or resultant force

State Newton’s second law

when a net force fnet, is applied to an object of mass, m it accelerates in the direction of the net force. The acceleration, a is directly proportional to the net force and inversely proportional to the mass.

State Newton’s third law

when object a exerts a force on object b, object b simultaneously exerts an oppositely directed force of equal magnitude on object a

Define normal force

The perpendicular force exerted by a surface on an object in contact with it

Define frictional force

The force that opposes the motion of an object

Define linear momentum

The product of the mass and velocity of an object

Define Newton’s second law of motion in terms of momentum

The net force acting on an object is equal to the rate of change of momentum.

Define elastic collision

A collision in which both momentum and kinetic energy is conserved

Define inelastic collision

A collision in which only momentum is conserved

State the law of conservation of linear momentum

The total linear momentum of an isolated system remains constant

Define impulse

The product of the net force and the contact time

Define work done on an object by a force

The product of the displacement and the component of the force parallel to the displacement

What is gravitational potential energy

The energy an object possesses due to its position relative to a reference point.

Define kinetic energy

The energy an object has as a result of the objects motion

What is mechanic energy

The sum of the gravitational and kinetic energy at a point

What is the law of conservation of energy

The total energy in a system cannot be created nor destroyed only transformed from one form to another

State the principle of conservation of mechanical energy

In the absence of air resistance or any external forces the mechanical energy of an object is constant

What is the work energy theorem

The work done by a net force on an object is equal to the change in the kinetic energy of the object

Define power

The rate at which work is done or the rate at which energy is transferred

Newtons law of universal gravitation

Every particle has its mass in the universe attracted every other particle with a force which is directly proportional to the product of their masses and inversely proportional to the square of the distance between their centers

Define gravitational field

The force acting per unit mass

State coulomb’s law

Two point charges exert forces on each other. The force is directly proportional to the product of their charges and inversely proportional to the square of the distance between their charges

what is an electric field

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

Define electric field

The force per unit positive charge

State coulomb’s law

Two point charges exert forces on each other. The force is directly proportional to the product of the charges and inversely proportional to the square of the distance between the charges

Describe an electric field

A region in space where 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 at a point

The force per unit positive charge

Define potential difference

The work done per unit positive charge

Define current

The rate of flow of charge

Define resistance

The opposition to the flow of electric current

State ohms law

The current through a conductor is directly proportional to the potential difference across the conductor at a constant temperature.

Define emf

The total energy supplied per coulomb of charge by the cell

State faradays law

The emf induced is directly proportional to the rate of change of magnetic flux

What exists around a permanent magnet or current carrying conductor?

A magnetic field

State lens law

The induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux

Why does the dc motor have a split ring

It allows current to switch direction every half turn so that the motor continues to rotate in one direction

Why does a generator have slip rings?

The slip rings allow the generator to maintain electrical contact with the external circuit

What does an ion core do

Increases the magnetic field by becoming magnetized itself

Describe the photoelectric effect

The process that occurs when light shines on a metal and electrons are ejected

What are photoelectrons?

Electrons that have been ejected from a metal

What is the significance of the photoelectric effect?

It illustrates the particle nature of light and establishes the quantum theory

Define threshold frequency

The minimum frequency of incident radiation at which electrons will be emitted from a particular metal

Define work function

The minimum amount of energy needed to Amit an electron from the surface to the metal

What does increasing the intensity of the light do to the electrons?

increasing the light intensity means more photons are hitting the metal per second which means more electrons will be ejected per second

What does increasing the frequency of the light do?

Increasing the frequency increases the energy per photon which increases the maximum kinetic energy

What are some ways to increase the magnitude of the induced emf

Increase the speed at which the coil moves or rotates, increase the number of turns in the coil, increase the magnitude of the magnetic field

What does increasing the frequency of the light do to the electrons?

Increasing the light frequency increases the energy per photon which increases the maximum kinetic energy