Physics

• Dissipation of kinetic energy

  When kinetic energy is lost as heat, such as when a moving object slows down due to friction or air resistance.
• Kinetic energy formula


  KE = 1/2 \* m \* v^2, where KE is the kinetic energy, m is the mass of the object, and v is the velocity of the object.
• Mass and kinetic energy

  The kinetic energy of an object is directly proportional to its mass, meaning that an object with a larger mass will have a greater kinetic energy.
• Velocity and kinetic energy

  The kinetic energy of an object is directly proportional to the square of its velocity, meaning that an object with a higher velocity will have a greater kinetic energy.
• Potential energy


  The energy that an object possesses due to its position or configuration. It is stored energy that can be converted into other forms of energy, such as kinetic energy.
• Types of potential energy


  Gravitational, elastic, and chemical potential energy are some examples of potential energy.
• Velocity


  A measure of an object's speed in a particular direction. It is a vector quantity, with both a magnitude (how fast the object is moving) and a direction (which way the object is moving).
• Linear acceleration


  A measure of how an object's velocity is changing over time. It is also a vector quantity, with both a magnitude (how much the velocity is changing) and a direction (which way the velocity is changing).
• Chemical energy


  A type of potential energy stored in the bonds of atoms and molecules that can be converted into other forms of energy during a chemical reaction.
• Emptied during a chemical reaction


  Transferred to the thermal store of the surroundings as heat energy.
• Kinetic energy


  KE = 1/2 x m x v^2
• Gravitational potential energy


  GPE = m x g x h
• Efficiency


  Useful energy out / Total energy
• Velocity


  v = x/t
• Acceleration


  a = (v-u)/t
• Acceleration equation: a = (v-u)/t
• Renewable energy sources


  • Solar
  • Wind
  • Hydro
  • Geothermal
  • Water
  • Waves
• Advantages of renewable energy


  • Generates electricity that produces no greenhouse gas emissions
• Disadvantages of renewable energy

  • High initial costs
• Non-renewable energy sources


  • Fossil fuels (coal, oil, natural gas)
  • Nuclear fuels
• Advantages of non-renewable energy


  • Provides more energy in comparison to renewable energy like wind energy
• Disadvantages of non-renewable energy


  • Will eventually run out if we keep using them
• Vector quantity


  Quantity with both magnitude and direction
• Scalar quantity


  Quantity with only magnitude
• Energy stores


  • Chemical
  • Gravitational potential
  • Thermal
  • Nuclear
  • Kinetic
  • Electrical
  • Elastic
  • Magnetism
• Energy transfers


  • Conduction
  • Convection
  • Radiation
• Kinetic energy


  Energy stored in a moving object
• Gravitational potential energy


  Energy stored in an object due to its position in a gravitational field
• Conduction


  • Heat energy transmitted through collisions between neighbouring atoms in a solid
• Convection


  • Heat energy transferred by the movement of fluids (liquids and gases)
• Radiation


  • Heat energy transferred by infrared radiation without any particles
• Efficiency


  Percentage of input energy that is usefully transferred
• Vector quantities
 Force (e.g. 20 N to the right) Force (e.g. 600 N downwards) Weight Velocity (e.g. 15 m/s downwards) Acceleration (e.g. 9.8 m/s²)
• Efficiency 
 Useful energy out /total energy in
• Efficiency of energy transfer = (useful energy out / total energy in) x 100
• Factors affecting braking distance
 Poor road conditions -oil on roads Less friction between tires & road Poor weather conditions-wet/icy roads Poor vehicle conditions-worn tread/tyres less friction between brakes & wheels
• Factors affecting thinking distance
 Tiredness Alcohol Medication Illegal drugs Distractions -texting, reading, adjusting the radio & general noise
• Stopping distance
 In an emergency, a driver must bring their vehicle to a stop in the shortest distance possible
• Stopping distance of cars
 Thinking distance Braking distance
• Energy cannot be created or destroyed, it can only be changed from one form to another