perhaps the simplest linkage is the lever, which is a link that pivots around a fulcrum attached to ground, or a fixed point. as a force rotates the lever, points far from the fulcrum have a greater velocity than points near the fulcrum. because power into the lever equals the power out, a small force applied at a point far from the fulcrum (with greater velocity) equals a larger force applied at a point near the fulcrum (with less velocity). the amount the force is amplified is called mechanical advantage. this is the law of the lever.