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OAR Mechanical Comprehension: Simple Machines Flashcards

7 cards from real OAR practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

Read the first 7 OAR Mechanical Comprehension: Simple Machines flashcards as text

  1. A wheel and axle consists of a large wheel attached to a smaller axle. If the wheel radius is 30 cm and the axle radius is 5 cm, what is the mechanical advantage?

    Answer: 6

    Mechanical advantage of a wheel and axle = wheel radius / axle radius = 30 / 5 = 6.

  2. A wedge is used to split a log. If you double the length of the wedge while keeping the same width, what happens to its mechanical advantage?

    Answer: It doubles

    Mechanical advantage of a wedge = length / width, so doubling the length doubles the mechanical advantage.

  3. Which class of lever has the fulcrum between the effort and the load?

    Answer: First class

    A first-class lever has the fulcrum positioned between the effort force and the load, like a seesaw.

  4. A screw with a pitch of 0.5 cm is turned with a screwdriver handle of radius 2 cm. What is the mechanical advantage (use π ≈ 3.14)?

    Answer: 25.12

    MA of a screw = 2π × radius / pitch = 2 × 3.14 × 2 / 0.5 = 25.12.

  5. In a fixed pulley system, what is the mechanical advantage?

    Answer: 1

    A single fixed pulley has a mechanical advantage of 1 — it changes direction of force but does not multiply it.

  6. A ramp is 10 meters long and rises 2 meters high. How much force is needed to push a 500 N box up the ramp (ignoring friction)?

    Answer: 100 N

    Force needed = weight × (height / length) = 500 × (2/10) = 100 N.

  7. Two gears mesh together. Gear A has 12 teeth and Gear B has 36 teeth. If Gear A turns at 90 rpm, how fast does Gear B turn?

    Answer: 30 rpm

    Output speed = input speed × (teeth on A / teeth on B) = 90 × (12/36) = 30 rpm.