Physics P1

• Speeds of different modes of transport

  • Walking: 1.4m/s
  • Running: 3m/s
  • Cycling: 5.5m/s
  • Cars in built-up areas: 13m/s
  • Cars on motorway: 31m/s
  • Aeroplanes: 250m/s
  • Trains: 55m/s
  • Wind Speed: 5.20m/s
  • Ferries: 15m/s
• Mass is scalar Q, kg, use mass balance
• Weight is vector Q, N, is a force acting on an object due to gravity, close to Earth and force caused by gravitational field around the Earth, use Newton meter
• What is the centre of mass? The point where whole mass is in concentration
• Waves transfer energy from one place to another without transferring any matter
• Advantages of Biofuels:

  Renewable

  Carbon neutral

  Reliable (crops take short time to grow and grow all year round), Continuously produced and stored for when needed
• Disadvantages of Biofuels

  Only carbon neutral if you keep growing plants/ raising animals at the rate that you are burning things

  Can't respond to immediate energy demands

  Refining is expensive (not enough space for crops grown for food)

  Forests cleared to grow biofuels so species losing natural habitats

  Decay/ burning increases ethane & carbon emissions
• What is a force?


  A push or pull on an object caused by it interacting with something
• What are non-contact forces caused by?

  Interactivity of fields.
• What do interacting magnetic fields cause?

  Attraction/ repulsion between magnetic forces and the electrostatic force causing attraction and repulsion between electrical charges due to interactions between their electric fields.
• 1m/s = 3.6km/h
• What is inertia?

  The tendency for motion to remain unchanged. Measures how difficult it is to change velocity of an object.

  m= f / a
• The force is always towards the centre of the circle in circular motion
• All light is reflected from the object's surface is transmitted by the filter
• All objects emit radiation, the intensity and distribution of these wavelengths depend on temperature
• Radiation emitted from bodies is spread out over a range of different frequencies and wavelengths
• A black body absorbs all incident radiation regardless of its frequency or angle of incidence.
• Red Giant/ Red Supergiant

  Hydrogen in the core runs out and because of gravity the force is larger than the pressure of thermal expansion. The star is compressed until dense and hot enough that hydrogen in its outer layer and helium in its core can go through fusion. This increases the pressure of thermal expansion until the outer layers of the star expand. Its becomes red because the surface cools.
• Supernova


  Big stars glow brightly again as they go through more fusion to make heavier elements. They expand and contract several times. Balance shifts between gravity and thermal expansion. Exploding into supernova.
• White Dwarf

  Medium-sized star lie Sun becomes unstable and ejects its outer layer of dense. Becoming hot, dense solid core. Small and emits light.
• Neutron Star or Blac Hole

  Exploding supernova throws layers of dust and gas into space, leaving very dense core called NEUTRON STAR. If star is massive, it will collapse and become BLACk HOLE. Super dense, not even light can escape from.