energy (SP3)*

• what is the definition of a vector?

  quanitities with magnitude and direction
• what is the definition of a scalar?

  quantities with only direction
• what are examples of scalars?

  • speed
  • distance
  • mass
  • energy
  • temperature
  • time
• what is the typical speed of walking, running, and cycling?


  • walking: 1.4m/s
  • running: 3m/s
  • cycling: 5.5m/s
• what is the equation for accelaration?


  a= (v-u)/t
• what is the area under a distance/time graph equal to?

  equal to the distance travelled in that time interval
• what is Newton's 1st law?

  a resultant force is needed to make something start moving, speed up, or slow down
• what is Newton's 2nd law?

  F = m X a
• what are examples of safety features in cars?

  • seat belts
  • air bags
  • crumple zones
• what is used to measure weight?

  newton meter
• what is the equation for weight?

  Weight = mass X gravitational field strength
• what is centripetal force?

  if an object is travelling in a circle, it is constantly changing direction and velocity. Meaning its always accelarating
• what is newton's 3rd law?

  each reaction has an equal and opposite reaction
• what is an object's intertial mass?


  measures how difficult it is to change the velocity of an object
• what is the equation for momentum?

  momentum = mass X velocity
• what is the conservation of momentum?

  in a closed system, the total momentum before an event an event is the same as after the event
• what is the equation for force?

  force = change in momentum / time
• what is the equation for stopping distance?

  stopping distance = thinking distance + braking distance
• what is the thinking distance?

  the distance the car travels in the driver's reaction time
• what factors can increase your reaction time?

  • tiredness
  • alcohol
  • drugs
  • distractions
• what is the braking distance?

  the distance taken to stop once the brakes have been applied
• how does the mass of the car affect the braking distance?

  the greater the mass means it won't stop as quickly
• what 3 factors will affect braking distance?

  • mass of the car
  • condition of the brakes
  • the amount of friction between tyres and roads
• what are the 8 energy stores?

  • kinetic
  • thermal
  • chemical
  • gravitational potential
  • elastic potential
  • electrostatic
  • magnetic
  • nuclear
• what are the 4 energy transfers?

  • mechanically
  • electrically
  • by heating
  • by radiation
• what is the equation for kinetic energy?


  KE = 0.5 X mass X (speed)^2
• what is the equation for the change in GPE?

  GPE = m X g X change in vertical height
• when is energy only useful?

  when its transferred from one store to a useful store
• what is the equation for efficiency?

  efficiency = useful energy transferred by device / total energy supplied to device
• what can reduce energy transferred by friction?


  lubrication
• what can reduce the rate of energy transferred by heating?

  insulation
• what are non-renewable energy examples?

  • fossil fuels
  • nuclear fuel
• what are renewable energy examples?

  • bio-fuels
  • wind
  • solar
  • hydro-electricity
  • tides
• what environmenal problems does non-renewable energy create?

  fossil fuels release carbon dioxide into the atmosphere when burned which adds to the greenhosue effect
• what are the advantages of renewable energy?

  • they will never run out
  • the damage they cause is less nasty than non-renewable
• what are bio-fuels?

  renewable energy resources created from either plant products or animal dung
• what are the disadvantages of bio-fuels?

  • high cost to refine them
  • forests cut down to make room to grow bio-fuels
• what are examples of vectors?

  force, velocity, displacement, weight, acceleration, and momentum
• what are examples of scalars?

  speed, distance, mass, energy, temperature, and time
• what are advantages of wind power?

  no pollution, minimal running costs