3.2.19

Work & Machines

Test yourself

Work and Machines

Machines have one fundamental limit: the conservation of energy.

Illustrative background for Conservation of energyIllustrative background for Conservation of energy ?? "content

Conservation of energy

  • The work done (or energy transferred) is given by the force × the distance moved by the object.
  • If we use a force multiplier to increase the force, we reduce the distance moved by the object.
  • This follows directly from the law of conservation of energy.
  • The law of conservation of energy says that energy cannot be created or destroyed. The work done is a constant.
Illustrative background for ResultsIllustrative background for Results ?? "content

Results

  • A long lever lets you move an object with greater force, but you can’t move it very far.
  • This is why doorknobs are far away from the door-hinges - it makes doors easier to open.
Illustrative background for ExampleIllustrative background for Example ?? "content

Example

  • A 20N force moves an object 10m.
  • A lever is then used to move the same object, but increases the force to 40N.
  • How far will the object move?
    • 20 × 10 = 200.
    • 200 ÷ 40 = 5
    • The object moves 5m.

Work and Machines

Machines have one fundamental limit: the conservation of energy.

Illustrative background for Conservation of energyIllustrative background for Conservation of energy ?? "content

Conservation of energy

  • The work done (or energy transferred) is given by the force × the distance moved by the object.
  • If we use a force multiplier to increase the force, we reduce the distance moved by the object.
  • This follows directly from the law of conservation of energy.
  • The law of conservation of energy says that energy cannot be created or destroyed. The work done is a constant.
Illustrative background for ResultsIllustrative background for Results ?? "content

Results

  • A long lever lets you move an object with greater force, but you can’t move it very far.
  • This is why doorknobs are far away from the door-hinges - it makes doors easier to open.
Illustrative background for ExampleIllustrative background for Example ?? "content

Example

  • A 20N force moves an object 10m.
  • A lever is then used to move the same object, but increases the force to 40N.
  • How far will the object move?
    • 20 × 10 = 200.
    • 200 ÷ 40 = 5
    • The object moves 5m.

Jump to other topics

1Biology

1.1Cells, Tissues & Organs

1.2Reproduction & Variation

1.3Ecological Relationships & Classification

1.4Digestion & Nutrition

1.5Plants & Photosynthesis

1.6Biological Systems & Processes

2Chemistry

2.1Particles

2.2Chemical Reactions

2.3Atoms, Elements, Compounds

2.4The Periodic Table

2.5Materials & the Earth

2.6Reactivity

2.7Energetics

2.8Properties of Materials

3Physics

3.1Energy

3.2Forces & Motion

3.3Waves

3.4Electricity & Magnetism

3.5Matter

3.6Space Physics

4Thinking Scientifically

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