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OAR Mechanical Comprehension: Simple Machines Questions and Answers Flashcards

6 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 6 OAR Mechanical Comprehension: Simple Machines Questions and Answers flashcards as text

  1. A worker uses a wheel and axle to lift a bucket from a well. If the wheel has a radius of 30 cm and the axle has a radius of 5 cm, what is the mechanical advantage of this system?

    Answer: 6

    The mechanical advantage of a wheel and axle equals the wheel radius divided by the axle radius: 30/5 = 6.

  2. Which simple machine is represented by a doorstop being pushed under a door?

    Answer: Wedge

    A doorstop is a wedge, which converts force applied to its blunt end into forces perpendicular to its inclined surfaces.

  3. A screw has 8 threads per inch. What is the pitch of this screw?

    Answer: 1/8 inch

    Pitch is the distance between adjacent threads, calculated as 1 divided by the number of threads per inch: 1/8 inch.

  4. A 200-lb crate is pushed up a 10-foot ramp to a loading dock 4 feet high. Ignoring friction, how much force is required to push the crate up the ramp?

    Answer: 80 lb

    The ideal mechanical advantage of an inclined plane is length/height (10/4 = 2.5), so the required force is 200/2.5 = 80 lb.

  5. In a compound pulley system with 4 supporting ropes, how much effort is ideally needed to lift a 240-lb load?

    Answer: 60 lb

    In an ideal compound pulley, the effort equals the load divided by the number of supporting ropes: 240/4 = 60 lb.

  6. A first-class lever has the fulcrum placed 2 feet from the load and 6 feet from the effort. If the load weighs 150 lb, what effort is needed to balance the lever?

    Answer: 50 lb

    Using the lever principle, effort × effort arm = load × load arm, so effort = 150 × 2/6 = 50 lb.