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Grade 8 · Science · Unit 6 of 8

Hydraulics & Pneumatics

Machines and bodies that move fluids

What your child practises

How hydraulic systems (liquids) and pneumatic systems (compressed air) work, where each is used, and how valves, pumps and tubes in machines compare with the heart, lungs and blood vessels.

Nova Scotia Curriculum learning outcome: Hydraulic and Pneumatic Systems · hydraulic and pneumatic systems

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

    Large trucks and buses often use air brakes. What is one advantage of air as the working fluid?

    • Air is denser than oil.
    • Air is more viscous than brake fluid.
    • Air is free, plentiful and does not spill.
    • Air cannot be compressed.

  2. Question 2

    Which part of the heart has a job like a valve in a machine?

    • the skin of the heart
    • the blood itself
    • the heart valves that keep blood flowing one way
    • the ribs

  3. Question 3

    A pneumatic system leaks. Compared with a hydraulic leak, what is likely true?

    • It always leaves a mess of oil.
    • Air escapes without leaving oil on the ground.
    • It can only lift the heaviest loads.
    • It makes water.

  4. Question 4

    A valve in a hydraulic or pneumatic system is used to…

    • make the fluid colder
    • change the fluid into a solid
    • store the fluid forever
    • regulate or direct the flow of the fluid

  5. Question 5

    A hydraulic system uses a…

    • magnet
    • liquid, usually oil
    • solid rod only
    • compressed gas

  6. Question 6

    Why do hydraulic systems use liquids instead of gases?

    • Gases cannot be used in machines.
    • Liquids are lighter than gases.
    • Liquids can be squeezed easily.
    • Liquids are almost incompressible, so force is passed on strongly and quickly.

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