Physics

• When analysing markets, a range of assumptions are made about the rationality of economic agents involved in the transactions
• The Wealth of Nations was written

  1776
• Rational


  (in classical economic theory) economic agents are able to consider the outcome of their choices and recognise the net benefits of each one
• Rational agents will select the choice which presents the highest benefits
• Consumers act rationally by


  Maximising their utility
• Producers act rationally by


  Selling goods/services in a way that maximises their profits
• Workers act rationally by


  Balancing welfare at work with consideration of both pay and benefits
• Governments act rationally by


  Placing the interests of the people they serve first in order to maximise their welfare
• Rationality in classical economic theory is a flawed assumption as people usually don't act rationally
• A firm increases advertising

  Demand curve shifts right
• Demand curve shifting right

  Increases the equilibrium price and quantity
• Marginal utility


  The additional utility (satisfaction) gained from the consumption of an additional product
• If you add up marginal utility for each unit you get total utility
• -1.6 x 10-¹⁹C

  Electron charge
• FORMULAE


  • MOTION
  • WORK, ENERGY AND POWER
  • WAVES, SOUND AND LIGHT
  • ELECTRIC CIRCUITS
• MOTION


  1. a = (vf - vi) / Δt

  2. x = vi Δt + 1/2 a Δt^2

  3. vf^2 = vi^2 + 2a Δx

  4. x = (vi + vf) Δt / 2
• WORK, ENERGY AND POWER

  • Potential Energy = mgh
  • Kinetic Energy = 1/2 mv^2
• WAVES, SOUND AND LIGHT


  • Wave speed = frequency x wavelength
  • Frequency = 1 / period
  • Energy = hf or hc/λ

  
• Amplitude


  What the human ear perceives as volume (loudness)
• Sound waves are reflected by large hard flat surfaces such as buildings walls and cliffs
• Echo


  Reflection of sound wave
• Ultrasound refers to sound waves of a higher frequency than we can hear (20 kHz to 100 kHz)
• Uses of ultrasound


  • Treatment of sports injuries
  • Imaging in pregnancy
• Amplitude


  What the human ear perceives as volume. Measured in decibels (dB). A high volume = large amplitude. A low volume = small amplitude.
• Echoes


  Sound waves are reflected by large hard flat surfaces such as buildings walls and cliffs. The reflection of the sound wave is known as an echo. An echo can be used to calculate unknown distances.
• When a wave reflects/echoes, the wave had to travel to the object and back. It has therefore travelled double the distance between the source and the reflection surface.

  
• Ultrasound


  Refers to sound waves of a higher frequency than we can hear (20 kHz to 100 kHz)
• Uses of ultrasound


  • Treatment of sports injuries: waves are fed through the skin to increase blood flow to the injured area
  • Imaging in pregnancy: When an ultrasound wave encounters a boundary in a medium, part of the wave is reflected, part absorbed and part is transmitted through the boundary. The reflected waves are detected in the same way as echoes and can be used to form an image (sonar imaging)
  • Bats: use ultrasound to locate insects and to navigate in the dark
  • Boats: use sonar to locate fish and measure the depth of the ocean
• Calculating depth using echo

  1. Measure time taken for echo

  2. Use speed of sound in water (1480 m/s)

  3. Depth = (speed x time) / 2
• Magnetic field


  A region in space where another magnet or ferromagnetic material will experience a non-contact force
• Magnet


  An object with a pair of opposite poles, called north and south
• Magnets


  • Magnets can be made from ferromagnetic materials, which are strongly attracted by magnets and are easily magnetised

  Like poles repel, unlike poles attract
• Magnetic field lines


  Imaginary lines around a magnet indicating the direction and strength of the magnetic field. They come out of the north pole and enter the south pole, forming a continuous loop.
• Properties of magnetic field lines

  • Imaginary, continuous, 3 dimensional, never cross or touch, arrows indicate direction (N to S), more concentrated at the poles
• Earth's magnetic field


  The Earth behaves as if it has a giant bar magnet running through it, with the magnetic field looping around the Earth. The compass needle points to the magnetic north pole, which is actually the south pole of the Earth's imaginary magnet.
• The angle between the true North Pole and the magnetic North Pole is called the angle of declination.
• Geographical north pole


  The point in the northern hemisphere where the rotation axis of the Earth meets the surface.
• Magnetic north pole


  The point where the magnetic field lines of the Earth enter the Earth. It is the direction in which a compass needle points.
• The sun releases particles (mainly electrons and protons) which travel outwards in all directions at speeds of up to 900 m/s. More particles are released during a solar storm called a coronal mass ejection.
• Magnetic North Pole of the Earth


  The South pole of the imaginary magnet through the Earth