Kinematics and Kinetics in Human Movement Practice Test 2026 - Free Practice Questions and Study Guide

In a lever system, the key is where the fulcrum (axis) sits relative to the effort and the load. For a first-class lever, the fulcrum lies between the effort and the resistance. Because the distances from the fulcrum to each force can change, the mechanical advantage isn’t fixed—it can be greater than one if the effort arm is longer, less than one if the load arm is longer, or exactly one if the arms are equal. This arrangement is what lets you trade force for distance and speed, such as in neck movements where the head is moved by muscles acting through a fulcrum between them and the head’s weight.

That’s why the statement describing the axis between effort and resistance with a mechanical advantage that may vary is the best fit. The other setups describe different lever classes: when the load is between the fulcrum and effort, you’d be looking at a different class; when the effort is between the fulcrum and load, that’s another class altogether.