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Grade 8 · Science · Unit 11 of 13

Simple Machines & Advantage

Levers, ramps, pulleys and mechanical advantage

What your child practises

Identifying the six simple machines, finding mechanical advantage from input and output forces, understanding that machines trade force for distance, and how innovations such as combine harvesters and robotics raised productivity.

Ontario Curriculum expectation: D2.6, D2.9 · input and output forces, mechanical advantage of simple machines and technological innovations that increased productivity

Sample questions

A taste of this unit. In the app, questions change every time and get easier or harder to match your child.

  1. Question 1

    Which is a technology that increased farm productivity?

    • the hand sickle only
    • the paper map
    • the wooden spoon
    • the combine harvester, which cuts and separates grain in one pass
    Show answer

    the combine harvester, which cuts and separates grain in one pass

    Hint: One machine can harvest much more grain per hour than hand tools.

  2. Question 2

    How have robotic arms in car factories changed productivity?

    • They make every car different by hand.
    • They can weld and assemble the same part quickly and repeatedly.
    • They need no electricity.
    • They are never programmed.
    Show answer

    They can weld and assemble the same part quickly and repeatedly.

    Hint: Automation raises output but also changes the jobs people do.

  3. Question 3

    Mechanical advantage is the ratio of…

    • input force to time
    • mass to volume
    • output force to input force
    • work to energy
    Show answer

    output force to input force

    Hint: Mechanical advantage = output force ÷ input force.

  4. Question 4

    Which part of a lever is the pivot?

    • the effort
    • the fulcrum
    • the load
    • the wheel
    Show answer

    the fulcrum

    Hint: The load and the effort act on either side of the fulcrum, depending on the lever.

  5. Question 5

    An input force of 40 N lifts a load that needs 120 N. What is the mechanical advantage?

    answer box

    Show answer

    3

    Hint: Mechanical advantage = output force ÷ input force.

  6. Question 6

    A machine has a mechanical advantage of 3. You apply an input force of 30 N. What output force does it give, in N?

    answer boxN

    Show answer

    90 N

    Hint: Output force = input force × mechanical advantage.

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