P3 - Mindmap in GCSE Science

Created by: xxeli123xx
Created on: 20-04-17 18:22

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Forces of Transport
- Speed and Distance
  - Speed is the distance travelled in a certain time
  - Distance = speed x time
  - Average Speed = (u +v) / 2
- Distance Time Graphs
  - Gradient = Speed
  - Steeper gradient = faster
  - Negative line = change in direction
  - Curves = acceleration or deceleration
  - Flat = Stationary
- Speed and acceleration
  - Acceleration is how quickly the speed in changing.
  - Acceleration = change in speed / time
  - Velocity is speed and direction of an object
  - Relative velocity is the difference between their velocities.
- Speed Time Graphs
  - Gradient = Acceleration
  - Flat section = steady speed
  - Steeper gradient = greater acceleration or deceleration
    - Uphill = acceleration
    - Downhill = declaration
  - Distance travelled = area under graph
- Mass, Weight and Gravity
  - Value of gravity of earth is 10m/s (squared)
  - Gravity gives an object its weight. Its caused by the pull of gravity.
    - Weight is a force measured in N
    - Mass isn't a force and is measured in kg
  - Weight = mass x gravitational field strength
- Forces
  - Gravity and weight acts straight downwards.
  - Reaction Force from a surface = straight upwards
  - Thrust or push or pull due to an engine speeding something app
  - Drag or air resistance or friction which slows something down
  - Tension in a rope or cable
- Friction Forces and Terminal Speed
  - Friction occurs in 3 main ways.
    - Friction between solid surfaces which are gripping
    - Friction between solid surfaces which are sliding past each other
    - Resistance or drag from fluids (liquids or gases e.g. air)
  - The larger the object the larger the drag.
  - In a fluid: friction (drag) always increases as the speed increases.
  - An object doesn't start at its terminal speed.
    - 1. more acceleration than resistance.
    - 2. speed increases, resistance increases
    - 3. resistance reduces the acceleration until the forces are balanced.
    - 4. Terminal Speed
    - The greater the drag, the lower the terminal speed.
- Forces and Acceleration
  - Balanced forces = same speed, same direction
  - Unbalanced force = acceleration
    - The object will accelerate in the direction of the force.
    - Size of acceleration is measured by F=ma
    - This is Newtons 2nd law of motion
- Stopping Distance
  - Thinking distance + breaking distance
  - Thinking Distance is affected by 2 things
    - How fast you were going and how dopey you are.
  - Braking Distance is affected by 4 things
    - How fast your going, the mass of the vehicle, how good your brakes are and how good you r grip is.
  - Too avoid a crash you need to leave 'enough space'.
- Momentum
  - Mass x Velocity
  - The way a force acts on an object can affect the momentum
    - Force Acting (N) = CHANGE IN MOMENTUM (kg m/s) / TIME TAKEN FOR THE CHANGE TO HAPPEN (s)
- Car Safety
  - Brakes
    - ABS brakes help the driver keep control of the vehicle when braking.
      - Automatically pump on and off to stop wheels locking and preventing skidding.
      - Shorter braking distance
  - Crumple Zones at front and back which change shape
    - Absorb some of the cars energy by changing shape.
  - Seatbelts that stretch
    - Person's kinetic energy turns into elastic energy
  - Air Bags which inflate and squash
  - All safety features: change shape, absorb energy and reduce injuries
- Kinetic Energy
  - Depends on both mass and speed
    - Faster and heavier means a higher KE
  - 0.5 X MASS X SPEED (speed squared)
  - Kinetic energy transferred = work done by brakes
    - work done by brake = maximum braking force x braking distance
  - Double mass = Double KE
  - Double speed = Quadruple KE
  - Triple Speed = KE x 9 = braking distance is 9 times as long
- Falling Object and Roller Coasters
  - When something falls, its GPE is converted into KE
  - KE gained = GPE lost
    - 1/2 x m x Vsquared = m x g x h
  - A roller coasters GPE changes
    - At the top = most GPE
    - As it goes down its GPE turns to KE
- Power
  - Work Done / Time Taken
  - Measure of how quickly works being done.
  - Measured in Watts (W)
  - How much 'energy per second so watts' in the same as 'joules per second'.
  - Power = Force x Speed
- Fuel Consumption and Emissions
  - Size and design of car engines determine who powerful they are
  - Bigger or more powerful the engine, the more energy it transfers from its fuel every second
  - Higher fuel consumption
    - more expensive
    - higher pollution = more fossil fuels
  - Fuel consumption depends on: size of engine, how cars driven, mass of car and road conditions.
  - Cars work better at certain speeds = 40mph - 55mph
  - Fossil fuels burnt, they release emissions
    - Carbon Dioxide, Nitrogen dioxide and water vapour.
    - Cause problems like acid rain and global warming
    - higher the fuel consumption, the great the emissions, the worse for the environment
- Fuels for Cars
  - Emissions released can cause climate change
    - Linked to greenhouse gases such as carbon dioxide in the atmosphere
  - Fossil fuels are non renewable
    - In the future we may rely on biofuel or solar power
      - Biofuels are made from plants and organic waste and are renewable
        Give off carbon dioxide, but plants also take in CO2 so there is no overall intake
  - Large batteries to power electric motors
    - Release no pollution, but batteries need to be charged
      - Electricity comes from power stations which burn fossil fuels
  - Solar powered vechiles = no pollution
    - Not as good as normal cars
Distance Time Graphs
- Gradient = Speed
- Steeper gradient = faster
- Negative line = change in direction
- Curves = acceleration or deceleration
- Flat = Stationary

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P3

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