Forces

• Define scalar quantity

  Scalar quantities have magnitude (size) only
• Define vector quantity

  Vectors have both magnitude (size) and direction
• Give an example of a non-contact force

  Gravitational force, electrostatic force and magnetic force
• What is a resultant force?

  A single force that represents a number of forces acting on an object
• What is the difference between mass and weight?

  Weight depends on gravitational field strength whereas mass remain the same
• What is the equation linking weight, mass and gravitational field strength?

  Weight = mass x gravity
• What are the units for weight?

  N or Newtons
• What are the units for mass?

  kg or kilograms
• What are the units for gravitational field strength?

  N/kg
• What is equation linking work done, force and distance?

  Work done = force x distance
• What are the units for work?

  J or Joules
• What are the units for force?

  N or Newtons
• What are the units for distance?

  m or metres
• How do you convert between Joules and Newton-metres?

  1 joule = 1 newton-metre
• What happens to an elastic object up to the limit of proportionality?

  Elastic deformation (It is able to return to its original length)
• What happens to an elastic object after the limit of proportionality?

  Inelastic deformation (It will not return to its original length)
• What is equation linking force, the spring constant and extension?

  Force = spring constant x extension
• What the units for the spring constant?

  N/m
• What are the units for extension?

  m or metres
• What are the units for elastic potential energy?

  J or Joules
• What is a fluid?

  a liquid or a gas
• Can a fluid be compressed?

  Yes
• What is equation linking pressure, force and area?

  Pressure = Force ÷ Area
• What are the units for pressure?

  N/m2
• What are the units for force?

  Newtons
• What are the units for area?

  m2
• Is distance a scalar or vector quantity?

  Scalar
• Is displacement a scalar or vector quantity?

  Vector
• Is speed a scalar or vector quantity?

  Scalar
• Is velocity a scalar or vector quantity?

  Vector
• What is distance?

  How far an object moves
• What is displacement?

  Both distance and Direction
• What is the equation linking distance, velocity and time?

  speed = distance ÷ time
• What are the units for distance?


  m or metres
• What are the units for speed?

  m/s
• What are the units for velocity?

  m/s
• How is speed different from velocity?

  velocity has direction, speed does not
• What are the units for time?

  s
• How do you calculate the speed of an object from a distance-time graph?

  by calculating the gradient (change in y divided by change in x)
• When can an object have constant speed but still be accelerating?

  If the object is travelling in a circle