Lever and pulley

In short: Levers and pulleys are simple machines that save force but lengthen the distance. The work stays the same: what you save in force you pay for in distance.

In more detail: For a lever: force times force arm equals load times load arm. The longer the lever arm, the less force is needed.

In detail

• Everyday levers: Crowbar, seesaw, scissors, pliers, bottle opener, wheelbarrow.
• One-sided and two-sided: In a two-sided lever the pivot lies between force and load (seesaw), in a one-sided one both are on the same side (wheelbarrow).
• Fixed and movable pulley: The fixed pulley only changes the direction of force, the movable pulley halves the force at double the pull distance.
• Block and tackle: Several pulleys multiply the effect. With four supporting rope sections you need only a quarter of the force.
• Golden rule: No device saves work, only force (schiefe-ebene-und-keil).