Mechanisms based on levers and linkages: the three classes of lever, mechanical advantage and velocity ratio, the principle of moments applied to levers, and linkages (reverse motion, parallel motion, bell crank) that change the direction or type of motion.

A Component 01 lever calculation. Marks for the mechanical advantage, the method and the effort with units.

For an ideal lever, mechanical advantage equals the effort arm divided by the load arm: $\text{MA} = \frac{0.60}{0.10} = 6$. Using the principle of moments, $\text{effort} \times \text{effort arm} = \text{load} \times \text{load arm}$, so $\text{effort} = \frac{450 \times 0.10}{0.60} = \frac{45}{0.60} = 75$ N. (Equivalently, effort = load divided by MA = $\frac{450}{6} = 75$ N.)

A common dropped mark is inverting the mechanical advantage (load arm over effort arm) or omitting the unit; MA is effort arm over load arm, and a value above 1 means a small effort moves a large load.

A Component 01 application question. Marks for each class and the explanation of the arrangement.

A pair of scissors is a first-class lever: the fulcrum (the pivot/rivet) is between the effort (the hand on the handles) and the load (the material being cut). A wheelbarrow is a second-class lever: the load (the contents) is between the fulcrum (the wheel) and the effort (the hands lifting the handles), which gives a large effort arm and a mechanical advantage greater than 1, so a small effort lifts a heavy load. The difference is the order: first class has the fulcrum in the middle; second class has the load in the middle (and third class has the effort in the middle, as in tweezers, favouring speed and range over force).

A common dropped mark is confusing second and third class; the middle component names the class only for first (fulcrum), and for second it is the load, for third the effort.