physics quiz

• Vectors


  Measurements that have both magnitude and direction (e.g. acceleration, force, momentum)
• Scalars


  Measurements that only have magnitude (e.g. mass, energy, temperature)
• Vectors


  • Acceleration
  • Force
  • Momentum
• Scalars


  • Mass
  • Energy
  • Temperature
• Difference between distance and displacement

  Displacement has direction, distance does not
• Difference between speed and velocity

  Velocity has direction, speed does not
• Vectors can be added to find a resultant vector
• If vectors are in opposite directions, one must be negative
• Weight


  Force = Mass x Gravitational field strength, measured in Newtons
• Gravitational field strength (g)

  9.8 N/kg on Earth
• Work done


  Energy transferred, measured in Joules, equal to Force x Distance
• Gravitational potential energy (GPE)


  Work done = Weight x Height, measured in Joules
• Hooke's Law


  Force = Spring constant x Extension
• Spring constant


  Measure of stiffness, in N/m
• Displacement-time graph


  Gradient = Velocity
• Velocity-time graph


  Gradient = Acceleration, Area = Displacement
• Newton's 3 Laws of Motion

  • No resultant force, no acceleration
  • Force = Mass x Acceleration
  • Every action has an equal and opposite reaction
• Factors affecting stopping distance

  • Thinking distance (increased by speed, distractions, alcohol/drugs, tiredness)
  • Braking distance (increased by speed, poor brakes/tyres, road/weather conditions)
• Momentum


  Mass x Velocity, conserved in collisions
• Force-momentum relationship


  Force = Change in momentum / Time
• Airbags


  Increase collision time, reducing force
• Rutherford's discovery about the atom

  • Mostly empty space, with a small positive charge at the centre (nucleus)
• Types of radiation


  • Alpha (stopped by paper)
  • Beta (stopped by aluminium)
  • Gamma (stopped by lead/concrete)
• Nuclear decay equations


  Uranium-230 -> Thorium-230 + Alpha

  Uranium-230 -> Thorium-230 + Beta
• Sources of background radiation

  • Cosmic rays
  • Radon gas
  • Medical equipment
  • Nuclear weapons
  • Some foods (e.g. bananas)
• Half-life


  Time for activity to decrease by half
• Longitudinal waves


  Oscillations parallel to direction of travel (e.g. sound)
• Transverse waves


  Oscillations perpendicular to direction of travel (e.g. light)
• Wave speed calculation


  Wave speed = Frequency x Wavelength
• Electromagnetic spectrum


  • Radio waves
  • Microwaves
  • Infrared
  • Visible light
  • Ultraviolet
  • X-rays
  • Gamma rays
• Electromagnetic spectrum properties


  Radio waves have longest wavelength, gamma rays have highest frequency and energy
• Light entering a glass block

  Refracts, slows down, wavelength shortens, bends towards normal
• Locating image formed by a lens

  Draw ray parallel into lens, through focal point, and through centre of lens
• Real and virtual images

  Real image: can be projected, inverted, diminished

  Virtual image: cannot be projected, upright, magnified
• Fate of a star larger than the Sun when its fuel runs out
• Centripetal force and velocity

  Centripetal force points towards centre, velocity is tangential
• Geostationary orbit


  Satellite has 24-hour period matching Earth's rotation, above the equator
• Red shift of galaxies as evidence for the Big Bang