Moments and Levers

• How does a force cause an object to rotate?

  • a force is applied on one side of a pivot and it rotates anticlockwise or clockwise
  • ie child on a see saw or turning the handle on a spanner
• What is a moment?

  • a turning effect of a force about a pivot
• what is the moment equation?

  M=F x d

  • Moment - Nm
  • Force - N
  • distance of force to the pivot - m
• why is a door handle placed on the oppposite side to the hinge?

  • The perpendicular distance is larger
  • so a larger moment is created so its easier to open the door
• what are the principles of moments?

  • if an object is balanced, the total clockwise moment about a pivot equals the total anticlockwise moment about that pivot
• what are levers?

  • increase the size of a force acting on an object to make the object turn more easily
• how can a lever be made to work better?

  • increase the size of the force applied
  • increase the distance of the force from the pivot
• how does a bottle opener work as a lever?

  • the lever increases the force applied on the bottle top
  • it does this by increasing the length/line of action from the pivot
• what are gears?

  • increase the effect of a turning force by using momentum
  • consist of wheels which rotate on an axle
  • the wheels fit and turn eachother
  • this means that as one gear turns, the other one also turns - however, the moment on the gears will not be the same