Forces

• scalar quantities only have magnitude (size)
• vector quantities have magnitude and direction
• displacement is the distance and direction from an objects initial position to its new position
• velocity is the speed in a certain direction
• scalar quantities:

  • temperature
  • time
  • distance
  • energy
• vector quantities:

  • weight
  • acceleration
  • velocity
  • displacement
• Newtons First Law - every object will remain at rest unless compelled to change its state by the action of an external force
• Newtons Second Law - Force = Mass x Acceleration
• Newtons Third Law - whenever two objects interact, the forces they exert on eachother are opposite and equal
• the centre of mass is the point at which all of the mass may be considered to act
• the acceleration of an object is a measure of how quickly its velocity changes
• acceleration is a vector quantity, negative acceleration (deceleration) means the object is slowing down
• uniform acceleration means an object is accelerating at a constant rate
• stopping distance is the distance a vehicle travels from the moment that the driver spots a hazard
• thinking distance is how far a vehicle travels in the time it takes a driver to react
• breaking distance is the distance a vehicle takes to stop after brakes are applied
• stopping distance = thinking distance + braking distance
• air resistance is drag in air and is a type of friction
• the resultant force on a falling object is the sum of weight and drag
• weight is the pull of gravity on an object