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Physics - Coggle Diagram

- - - - Distance covered per unit time
      - average speed(m/s) = total distance(m)/total time(s)
      - Standard unit is m/s
      - Velocity
        
        Speed of an object in a certain direction
    - - Rate of change of velocity
      - Standard unit is m/s²
      - acceleration = change in velocity(m/s)/time taken(s)
    - - Distance-time graphs
        
        Distance is y-axis
        
        Time is x-axis
        
        Gradient of a distance-time graph = speed
        
        Gradient = rise/run
      - Speed-time graphs
        
        Speed is on the y-axis
        
        Time is on the x-axis
        
        Area under line = distance
        
        Gradient = acceleration
    - - acceleration of gravity(free fall) = 10 m/s²
      - Terminal velocity
        
        The top speed of an object experiencing air resistance or a similar resistant force
        
        3 stages of reaching terminal velocity
        
        1) The acceleration is (almost) constant as air resistance is negligible
        
        2) The graph line curves, showing decreasing acceleration as air resistance increases
        
        3) Terminal velocity is reached when there is no resultant force and speed is constant
  - - - Weight is the pull of gravity on a body
      - Measured in newtons
      - weight (N) = mass(kg) x gravitational field strength (N/kg)
    - - Measure in kg
      - A measure of matter in a body
  - - - If the average density of an object is greater than water (1 g/cm³), it will sink. If the average density is less than that of water, it will float
  - - - Forces can...
        
        Increase or decrease the speed of a body
        
        Change the shape of a body
        
        Change the size of a body
        
        Change the direction of movement of a body
      - Measured in Newtons (N)
      - Resultant force
        
        The sum or total of 2 or more forces acting on a body
        
        unbalanced forces = resultant force --> change in speed
        
        balanced forces = no resultant force --> constant speed (or remains at speed of zero)
      - Forces are vectors
        
        Measurements with a size and a direction
    - - Contact forces
        
        Push/pull forces
        
        Thrust
        
        Up-thrust/lift
        
        Buoyancy
        
        Tension
        
        Torque
        
        Resistive forces
        
        Friction
        
        Drag/air resistance
        
        Force of friction between the air and the object moving through it
        
        Reaction/normal
      - Non-contact forces
        
        Weight
        
        Magnetic force
        
        Electrostatic force
        
        Nuclear force
    - - force(N) = spring constant (N/m) x extension (m)
      - When a spring is stretched to much and begins to deform and the line on the extension-load graph begins to curve, it is called the limit of proportionality
        
        After this point, Hooke's law does not apply
    - - Moments
        
        moment(Nm) = fore(N) x perpendicular distance to the pivot (m)
        
        Principle of moments
        
        A system will not rotate if the clockwise and anti-clockwise moments are equal
      - Equilibrium
        
        A body is in equilibrium if there are no net forces and no net moments
      - Centre of mass
        
        The average position of all mass in an object
        
        For uniform objects and regular shapes, the centre of mass is at. point along the line of symmetry
        
        Stability
        
        Position of centre of mass effects the stability of an object
    - - Vectors
        
        Measurements with a size and a direction
        
        Acceleration
        
        Forces
        
        Displacement
        
        Velocity
        
        Momentum
        
        Weight
      - Scalars
        
        Measurements with just a size
        
        Energy
        
        Power
        
        Pressure
        
        Distance
        
        Speed
        
        Time
        
        Mass
  - - - Law of conservation of momentum
        
        In any collision, the total momentum before and after the collision is the same
    - - Change in momentum of a system
      - impulse = mv - mu
- - - - Energy stored in moving objects
      - k.e(J) = 1/2 x mass(kg) x velocity(m/s)²
    - - Energy stored in the bonds of chemical compounds and released in chemical reactions
    - - Energy stored when we stretch, bend or compress something elastic
    - - Energy stored in every atom and released during nuclear fission or nuclear fusion
    - - Energy stored in a system
      - Sometimes called heat or thermal energy
    - - Energy stored in an object that is lifted upwards
      - g.p.e(J) = mass(kg) x acceleration of gravity (m/s²) x change in height (m)
  - - - Mechanical work
        
        Forces making things move
      - Electrical work
        
        Electric currents
      - Waves
        
        Light and sound
      - Heat
        
        Such as from a gas cooker
    - - Principale of conservation of energy
        
        Energy cannot be created or destroyed, only converted from one store to another
      - It can be converted into waste energy such as heat or sound
  - - - Fossil fuels
        
        Coal, oil, gas
        
        Fossil fuels are burned to produce heat, which heats water to create steam. The steam causes turbines to spin, which cause a gngerator to spin at high speeds and generate electricity.
        
        Main source of global fuel
        
        Advantages
        
        Generate lots of energy
        
        Power stations can be constructed in any location
        
        Transporting oil and gas is easy
        
        Disadvantages
        
        Fossil fuels are non renewable
        
        Power stations produce a lot of pollution
        
        Pollution can contribute to acid rain
        
        Oil can produce environmental hazards
    - - Nuclear power stations produce electricity similar to regular power stations, however instead of burning fossil fuels, they use the fission of uranium or other radioactive materials to produce heat
      - Advantages
        
        Produces no polluting gases
        
        Does not contribute to global warming
        
        Very low fuel costs
        
        Technology research required benefits other industries
        
        Power station has a very long lifetime
      - Disadvantages
        
        Safe disposal of radioactive waste is difficult and expensive
        
        Thermal pollution from wastewater affects marine life
        
        Large-scale accidents can be catastrophic
        
        Costs of building and safely decommissioning are very high
        
        Cannot react quickly to changes in electricity demand
    - - Hydroelectric energy
        
        Water naturally flows from inland to the sea, downhill. Dams trap this water and then release it through a turbine. The spinning turbine is attached to a generator which creates electricity
        
        Advantages
        
        Renewable
        
        No harmful pollutants are produced
        
        Disadvantages
        
        Expensive
        
        Flooding of land around dam destroys local habitats or buildings
        
        Whilst water is in the reservoir, any vegetation in it will rot and produce methane
      - Tidal energy
        
        Large barriers over river estuaries trap water. At high and low tide the water is allowed to flow in or out, turning turbines, which turn generators and generate electricity
        
        Advantages
        
        Renewable energy resource
        
        No fuel costs
        
        No harmful polluting gases are produced
        
        Tidal power is reliable
        
        Disadvantages
        
        Do not produce large amounts of electricity
        
        Can only be used to generate electricity a few times per day
        
        Damage habitats of shore dwelling animals
      - Wave energy
        
        Uses the movement of waves to drive turbines and produce electricity
        
        Advantages
        
        Renewable energy source
        
        No fuel costs
        
        No harmful polluting gases produced
        
        Disadvantages
        
        Do not produce large amounts of electricity
        
        Unreliable as size of waves vary
        
        Damage habitats of shore dwelling animals
    - - Solar cells
        
        Produce electricity directly from sunlight
        
        Only work when there is sunshine
      - Solar panels
        
        Black surfaces that absorb heat from the sun to warm up water for homes
      - Advantages
        
        Renewable energy source
        
        No fuel costs
        
        No harmful polluting gases are produced
        
        Provide electricity in remote locations
      - Disadvantages
        
        Solar cells are expensive and inefficient
    - - Large blades turned by wind, turn a generator and produce electricity. The faster the blades turn, the more energy produced
      - Disadvantages
        
        Noisy and spoil the view
        
        Amount of energy produced is unreliable
        
        Wind farms built at sea are expensive and damage animals; habitats
      - Advantages
        
        Renewable energy source
        
        No fuel costs
        
        No polluting gases produced