physics AS

• Waves


  Transfer energy without transferring matter
• Types of waves


  • Transverse
  • Longitudinal
• Transverse waves


  Particles oscillate perpendicular to the direction of energy transfer. example is seismic S waves
• Longitudinal waves


  Particles oscillate parallel to the direction of energy transfer, made up of compressions and rarefactions. example of this are sound waves
• Time period


  Time taken for one complete wave to pass a point
• Frequency


  Number of complete waves passing a point every second, calculated as 1 / time period
• Wave speed


  Equals frequency times wavelength (V = f * Lambda)
• Polarization


  Transverse waves can be polarized by a filter that only transmits waves oscillating in a particular direction
• Interference/Superposition


  When displacements of individual waves sum at each point, can be constructive or destructive
• Harmonics


  Occur when wavelength is equal to 2x or 1x the length of the string
• Nodes and antinodes


  Nodes have destructive interference and no energy transfer, antinodes have both constructive and destructive interference with energy transfer
• Young's double slit experiment


  Uses coherent sources (in phase) at the double slit to produce a diffraction pattern, fringe width W = Lambda * D / s where D is distance and s is slit separation
• Single slit diffraction


  Has a large central maximum that falls away quickly, with smaller secondary maxima
• Diffraction grating


  Equation: n * Lambda = d * sin(Theta), where n is order, Lambda is wavelength, d is line spacing
• Refraction


  Equation: n1 * sin(Theta1) = n2 * sin(Theta2), where n1 and n2 are refractive indices of the two media
• Total internal reflection (TIR)


  Occurs when angle of incidence is greater than the critical angle, and the refractive index of the first medium is greater than the second
• Average speed


  Distance / time
• SUVAT equations


  Equations of motion for accelerating objects
• Projectile motion


  Vertical motion uses SUVAT, horizontal motion uses constant speed
• Newton's laws


  1st: Constant motion if no external force, 2nd: F=ma, 3rd: Action-reaction pairs
• Weight


  Force = mass * gravitational field strength
• Equilibrium


  No resultant force and no resultant moment
• Friction


  Increases with speed, force parallel to slope = mg*sin(Theta)
• Energy


  Kinetic = 1/2*mv^2, Gravitational potential = mgh
• Hooke's law


  Force = spring constant * extension
• Stress and strain


  Stress = force/area, Strain = extension/original length, Young's modulus = stress/strain
• Stress-strain graph


  Limit of proportionality, Elastic limit, Ultimate tensile stress
• Equilibrium


  Sum of clockwise moments = sum of anticlockwise moments
• Scalars and vectors


  Scalars have magnitude only, vectors have magnitude and direction
• Momentum


  p = mv, F = rate of change of momentum
• Conservation of momentum


  Total momentum before = total momentum after in closed systems
• Braking distance


  Quadruples if speed doubles due to kinetic energy
• Elastic and inelastic collisions

  Elastic conserves kinetic energy, inelastic does not
• Fundamental particles


  Leptons are fundamental, hadrons are made of quarks (baryons 3 quarks, mesons quark-antiquark)
• Strong nuclear force


  Keeps nucleus together, attractive up to 0.5 cm then repulsive, range 3-4 cm
• Mass-energy equivalence


  E = mc^2, mass can be converted to energy in annihilation
• Graviton


  Exchange particle for the gravitational force
• Strong nuclear force


  Force that keeps the nucleus of an atom together, overcoming the electrostatic repulsion of protons
• Strong nuclear force


  • Attractive up to 0.5 cm, then becomes repulsive
  • Range of attraction is 3-4 cm
• Mass-energy equivalence


  Mass can be converted into energy, and vice versa, according to the equation E = mc^2