physics sags Flashcards
Scalar
A physical quantity that has magnitude only
Vector
A physical quantity that has both magnitude and direction
Resultant vector
The single vector which has the same effect as the original vectors working together
Distance
The length of path travelled (scalar)
Displacement
A change in position (vector, points from initial to final position)
Speed
The rate of change of distance (scalar)
Velocity
The rate of change of position
Or the rate of displacement
Vector
Acceleration
The rate of change of velocity
Coulomb’s law
The force between two charges is directly proportional to the product of the charges and is inversely proportional to the square of the distance between them
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 a positive test charge would move if placed at that point
Electric field strength (magnitude)
The force per unit positive charge
Weight Fg
The gravitational force the earth exerts on any object on or near its surface
Normal force Fn
The perpendicular force exerted by a surface on an object in contact with it
Frictional force Ff
The force that opposes the motion of the object
Newton’s first law
An object continues in a state of rest or uniform velocity unless it is acted upon by a resultant force
Inertia
The property of an object that causes it to resist changes in its state of rest or uniform motion
Newton’s second law
Motion
When a force Fnet is applied to an object 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
Newton’s second law
Momentum
The net force acting on an object is equal to the rate of change of momentum
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
Momentum
The product of the mass and velocity of the object
The law of conservation of linear momentum
The total linear momentum of an isolated system remains constant
Elastic collision
A collision in which both momentum and kinetic energy are conserved
Inelastic collision
A collision in which only momentum is conserved
Impulse
The product of the net force and the contact time
Work
The product of the displacement and the component of the force parallel to the displacement
Gravitational potential energy
The energy an object possesses due to its position relative to a reference point
Kinetic energy
The energy an object has as a result of the objects motion
Mechanical energy
The sum of gravitational potential and kinetic energy at a point
The law of conservation of energy
The total energy in a system cannot be created or destroyed, only transferred from one form to another
The principle of conservation of mechanical energy
In the absence of air resistance or Amy external forces, mechanical energy of an object is constant
Work energy theorem
The work done by a net force on an object is equal to the change in kinetic energy of the object
Power
The rate at which work is done
The rate at which energy is transferred
1 Watt
The power when one joule of work is done in one second
Efficiency
The ratio of output power to input power
Newtons law of universal gravitation
Every particle in the universe attracts 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 centres
Potential difference
The work done per unit positive test charge
Current
The rate of flow of charge
Ohms law
Current through a conductor is directly proportional to the potential difference across a conductor at a constant temperature
Resistance
A materials opposition to the flow of electric current
Emf
The total energy supplied per coulomb of charge by the cell
Magnetic flux linkage
The product of the number of turns on the coil and the flux through the coil
Faradays law of electromagnetic induction
The emf induced is directly proportional to the rate of change of magnetic flux (flux linkage)
Lenz’s law
The induced current flows in a direction so as to set up a magnetic field to oppose the change in magnetic flux
Diode
A component that only allows current to flow in one direction
The photoelectric effect
The process when light shines on a metal and electrons are ejected
Threshold (cut off) frequency
The minimum frequency of incident radiation at which electrons will be emitted from a particular metal
Work function
The minimum amount of energy needed to emit an electron from the surface of a metal
Material specific
One Volt
Is the potential difference between two points where 1J of work is done per coulomb of charge transferred from some point to the other.
