Wedge, Screw, and Wheel & Axle
Wedge: Two inclined planes back-to-back. Splits, cuts, or secures. A thinner, longer wedge = greater MA. Examples: axe blade, knife, chisel, doorstop.
Screw: An inclined plane wrapped helically around a cylinder. Converts rotational force (torque) into linear motion. Pitch = distance between threads (advance per full rotation). Smaller pitch = more MA but more turns needed. MA = 2πr / pitch.
Wheel and axle: Large wheel + smaller axle rotate together. Turning the large wheel with small force creates large force at the axle. MA = wheel radius / axle radius. Examples: steering wheel, doorknob, winch, screwdriver handle.