Main Definitions Flashcards
Scalars
Quantity that can be described by just a size and unit
Vectors
A quantity that is described with size, unit and direction
Acceleration
The rate of change of velocity
Velocity
The rate of change of displacement
Projectile
An object that moves with constant horizontal velocity whilst simultaneously accelerating vertically due to gravity
Newtons 1st law
An object will remain at constant velocity unless acted upon by an unbalanced force
Newtons 2nd law
F=Ma
Newtons 3rd law
If A exerts a force on B then B will exert an equal but opposite force on A
Elastic collisions
Both momentum and kinetic energy are conserved. The kinetic energy before and after the collision is the same
Inelastic collisions
Momentum is conserved but kinetic energy isn’t. The kinetic energy after the collision is either greater or less than the kinetic energy before.
Impulse
The change in momentum of an object
Einsteins 1st postulate
The speed of light is constant to all observers no matter their velocity
Einsteins 2nd postulate
The laws of physics are the same for all freely moving observers
Law of conservation of energy
Energy cannot be created of destroyed, only changed from one form into another
Length contraction
A stationary observer will observe a moving object to have a shorter length than someone on the moving object
Doppler effect (sound)
The change in frequency of a wave caused by relative motion between the source and observer
Redshift
Wavelength of light is stretched so the light is seen as towards the red end of the visible spectrum
Hubbles law
Galaxies that are moving faster are further away from us as some galaxies are more redshifted than others
Coherent source
Waves that have a constant phase relationship
Critical angle
The angle of incidence such that the angle of reflection is 90 degrees
Irrandence
The power per unit area
Volt
One volt is one joule of work done moving one coulomb of charge between 2 points
Photoelectric effect
Evidence for the particular model of light
Proves how each photon of light contains a fixed amount of energy
Work function
The number of joules of energy is the minimum energy required for photons to be emitted
Threshold frequency
Minimum frequency of photons required to give photo emissions
Potential difference / voltage
The difference in the amount of energy that charge carriers have between two points in a circuit
Power
The energy used per second
EMF
The number of joules of energy given to each coulomb of charge which passes through the source
