Forces and work

• Entry Level Certificate
• Force


  A push or a pull that acts on an object because of another object
• Representing forces


  Forces can be shown with arrows; the arrow shows the direction of the force, and a longer arrow shows a bigger force
• Forces can be sorted into contact and non-contact forces
• Contact forces


  • Objects must be touching each other
  • Include friction
  • Air resistance
  • Tension
  • Normal contact force
• Normal contact force


  A force that supports an object in contact with a surface
• Non-contact forces


  • Act at a distance
  • Objects need not be touching
  • Include gravitational force
  • Magnetic force
  • Electrostatic force
• Gravitational force


  The force you feel on Earth that keeps you on the ground
• Skydivers know all about forces
• Gravitational force pulls skydivers down towards the Earth


  Air resistance pushes upwards against them
• Forces are measured in newtons, N
• Force meter


  A device used to measure forces
• A force is a push or a pull
• Normal force


  The chair pushes back up when you sit on it
• Contact forces


  • Friction
  • Air resistance
  • Normal contact force
• Non-contact forces


  • Gravitational force
  • Magnetic force
  • Electrostatic force
• Investigate how forces act on objects in your classroom
• Use a newton meter to measure the forces being applied
• The diagram shows a trampoline
• Force acting upwards


  Normal force
• Force acting downwards


  Gravitational force