Physics

• Longitudinal Waves


  Oscillations are parallel to the direction of energy transfer, consisting of compressions and rarefactions
• Longitudinal Waves


  • Sound
  • Ultrasound (Ultrasonic)
  • Infrasound
• Time Period


  Time taken to complete 1 round of wave, inverse of frequency
• Time Period


  1. time period = time taken / number of waves

  2. time period = 1 / frequency
• Law of Reflection


  angle of incidence = angle of reflection
• Refraction


  The change in the speed and direction of a wave once it passes through different mediums
• In refraction, the frequency ALWAYS remains the same
• Dispersion


  The refraction of light with different wavelengths at different angles, resulting in different colors of the rainbow
• Greater frequency


  Higher pitch
• Gas


  • Non-fixed shape, Non-fixed volume, Particles move at high speed, freely, at random
• Evaporation


  Occurs over a range of temperatures, Occurs ONLY at the liquid's surface, Causes cooling effect
• Brownian Motion


  When small particles (such as pollen or smoke particles) are suspended in fluids, the particles can be observed moving at random through a microscope. This motion is caused by the fluid molecules colliding at high speeds with the small particles.
• The effects of thermal expansion include length increases, area increases, and volume increases
• Gas


  • Expand significantly (due to there being no bonds holding the molecules together)
• Shiny and white things do not reflect heat, they reflect radiation. And vice versa with matt black things
• Types of energy stores

  • Magnetic
  • Internal (thermal)
  • Chemical
  • Kinetic
  • Electrostatic
  • Elastic potential
  • Gravitational potential
  • Nuclear
• Work done


  Whenever a force acts on an object that moves in the direction of the force, there is work done. Whenever any work is done, energy gets transferred from one form to another.
• Power (P)


  • The amount of energy transferred every second, unit watt (W) or joules per second.
  • P = energy transferred / time taken
• Mass and Weight


  • Mass is related to the amount of matter in an object, measured in kilograms (kg). Weight is the force of gravity on a mass, measured in newtons (N).
  • Weight = mass x gravitational field strength
• Average speed (ms-1)


  distance (m) / time (s)
• Average velocity (ms-1)


  displacement (m) / time (s)
• Period of a pendulum (s)

  total time (s) / number of swings
• Weight (N)


  mass (kg) × gravitational field strength (ms-2)
• Force (N)


  mass (kg) × acceleration (ms-2)
• Density (kgm-3)


  mass (kg) / volume (m3)
• Hooke's law: Force (N)


  constant (Nm-1) × extension (m)
• Pressure (Pa)


  force (N) / area (m2)
• Fluid Pressure (Pa)


  density (kgm-3) × gravitational field strength (ms-2 or Nkg-1) × height (m)
• Work (J)


  force (N) × distance moved (m)
• Power (W)


  work (J) / time (s)
• Kinetic Energy (J)


  1/2 × mass (kg) × velocity2 (ms-1)
• Gravitational potential energy (J)

  mass (kg) × gravitational field strength (ms-2 or Nkg-1) × height (m)
• Efficiency (%)


  useful power output (W) / total power input (W) × 100
• Efficiency (%)


  useful energy output (J) / total energy input (J) × 100
• Moment (Nm)


  force (N) × perpendicular distance from pivot (m)
• Momentum (kgms-1)


  mass (kg) × velocity (ms-1)
• Force (N)


  change in momentum (kgms-1) / time (s)
• Impulse (kgms-1 or Ns)

  change in momentum (kgms-1)
• Centripetal Force (N)


  mass (kg) × velocity2 (ms-1) / radius (m)
• Orbital Period (s)


  2 × π × radius (m) / velocity (ms-1)