8.1 Load and Effort, Mechanical Advantage, Velocity Ratio and Efficiency of a Simple Machine8.2 Effort and Load of an Ideal Machine8.3 The Lever8.4 Inclined Plane (Wedge)8.5 Screws8.6 Simple Screwjack8.7 Differential Screwjack8.8 Pulleys8.9 Differential Pulley8.10 Wheel and Axle8.11 Wheel and Differential Axle8.12 Examples