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Physics paper 2 - Coggle Diagram

- - - - a = Δv / t
      - gradient of a velocity-time graph
    - - s = v t
    - - gradient = speed
  - - - human reaction time ~ 0.2-0.9 seconds
      - affected by
        
        alcohol
        
        fatigue
        
        drugs
    - - affected by
        
        adverse road
        
        vehicle conditions
        
        weather
    - - thinking distance + braking distance
  - - - column of liquid
        
        p = h ⍴ g
    - - thin layer of air around the Earth
        
        pressure decreases with altitude
    - - a submerged object experiences a pressure below it
        
        the object is experiencing an upwards force called upthrust which can result to some objects floating
  - - - measured in kgm/s
      - p=mv
      - total momentum before and after any event must be equal
  - - - the sum of all the forces in all directions acting on an object
    - - the single point where an object's weight is said to act
    - - have both magnitude and direction
    - - measured in Nm
      - w=mg
    - - only have magnitude
  - - - F=ma
    - - every action has an equal and opposite reaction
    - - an object is at rest or at a constant velocity unless acted on by a resultant force
- - - - elements heavier than iron are made in a supernova
    - - red supergiant
        
        supernova
        
        neutron star
        
        black hole
    - - red giant
        
        white dwarf
        
        black dwarf
  - - - gravity acts towards the center of the orbit
        
        for circular orbits, the objects move at the same speed, but velocity is changing so the object accelerates
    - - for a stable orbit, orbital speed increases
  - - - inner planets are mostly rock, outer planets are mostly gas
      - Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune
- - - - force causes rotation
      - coil of current carrying wire in a magnetic field
      - force (N) = magnetic flux density (T) x current (A) x length (m)
    - - strong and uniform field inside
      - always produces a force of attraction
      - coil of wire with a current flowing through
    - - for a current carrying conductor at right-angles to a field
        
        Index finger: field
        
        middle finger: current
        
        thumb: force
  - - - converts vibrations in the microphone coil into current in a circuit
    - - process
        
        current flows, creating a magnetic field
        
        this interacts with a permenant field, producing a force which vibrates the core
    - - if a conductor or field move relative to each other, a potential is induced across the conductor
    - - if 100% efficient then input power=output power
    - - consists of:
        
        A metal core with a primary coil on one side and a secondary coil of wire on the other side
      - national grid
        
        V₁ x I₁ = V₂ x I₂
        
        power lines carry current at a very high voltage, to reduce the current, which improves efficiency by reducing the energy loss through heating
      - step-up
        
        n₁ > n₂
        V₁ > V₂
      - step-down
        
        n₁ < n₂
        
        V₁ < V₂
    - - generates alternating current
    - - generates direct current
  - - - iron steel, nickel, cobalt
    - - compass
        
        shows that the Earth's core is magnetic
        
        points in direction of Earth's magnetic north
      - generating electricity
        
        rotating a coil of wire through a magnetic field generates a current
  - - - becomes magnetic when placed in a field
    - - produces its own magnetic field
- - - - distance between two consecutive points on a wave
    - - v = f �
        
        speed - frequency x wavelength
    - - number of oscillations per second (Hertz)
    - - time taken for one wavelength to pass
        
        T = 1/ f
    - - max displacement from rest
  - - - seismic waves
        
        P-waves
        
        solids and liquids
        
        S-waves
        
        only solids
      - sound causes vibrations in the eardrum
        
        audible range: 20Hz - 20kHz
      - ultrasound
        
        above the frequency of human hearing
        
        used in foetal scanning, ultrasound is emitted
  - - - towards normal
        
        wave speed decreases
      - frequency is constant
      - away from normal
        
        wave speed increases
    - - angle of incidence = angle of reflection
  - - - propagation = transmission of motion, light, sound, etc. in a particular direction or through a medium.