Forces

• MA (mechanical advantage) is the ratio of the effort applied to the effort required to move a load. if the advantage is <1, there is a disadvantage. If it is >1, there is an advantage.

  $MA: L/E$

  Where L is load and E is effort.
• First class lever

  
• Second class lever

  
• Third class lever

  
• Velocity ratio is the distance the effort moves to the distance the load moves.

  VR = dₑ/dₗ
• In the physical world, a machine could never be perfectly efficient (MA ≠ VR). In the test, assume that all questions mean perfectly efficient machines.
• η = MA/VR * 100
• Assume moments for all levers.
• VR for inclined planes = 1/sinθ
• number of ropes in a puller system determines the VR of the system.