Glossary
mechanical advantage
Mechanical advantage is how much a machine multiplies the force you apply: a lever, gear or pulley trades distance for force, so a small effort raises a large load.
Mechanical advantage is the ratio between the load a machine moves and the effort put into it. A machine does not create work — it trades distance for force. Press the short arm of a lever through a small distance and the long arm sweeps a large distance with a small force; press the long arm and the short arm moves a little with a large force. Force gained is always paid for in distance moved.
Each simple machine expresses the ratio differently. For a lever it is the two arms, measured from the fulcrum. For a pulley system it is the number of rope segments holding the load: a single fixed pulley changes only the direction of the pull and has an advantage of one, and every added supporting segment lowers the effort while lengthening the rope you haul. For gears it is the tooth counts — a large gear driven by a small one turns slower and delivers more torque.
The reason to know the idea is that the picture carries it. The load, the effort and the pivot are almost always marked on an ASVAB diagram, so the ratio can be read off rather than calculated.
Taught in
Related terms
- torque — Torque is a turning force — a force applied at a distance from the axis it turns — measured in pound-feet, and a torque wrench tightens a fastener to a set value.
- inertia — Inertia is an object's resistance to any change in its motion; it grows with mass, so the heavier object is the harder one to start, stop or turn.
- lever — A lever is a rigid bar that turns about a pivot called a fulcrum. A long effort arm and a short load arm let it lift far more than the force you apply.
- friction — Friction is the force that opposes motion when two surfaces are in contact. It turns movement into heat, and it depends on the surfaces and how hard they are pressed together.
Source: Official ASVAB — subtest descriptions (what each subtest asks) and the CAT-ASVAB scored-question counts (accessed 2026-09)