Forces and Motion

Before you go any further

Physics Narrative for 11-14 Supporting Physics Teaching

Closing the door

Get up, walk to the nearest door and open it. Not so hard was it? You can probably do it with your little finger. Now close it, but this time try pushing very close to the hinge. Much harder. This is no longer a task which you can easily do with your little finger!

In both cases you have exerted a force on the door to turn it. The end result is the same, yet the forces exerted are very different. In pushing closer to the hinges a much bigger force is needed to close the door.

Try this simple demonstration out with your class: Challenge the biggest and strongest pupils to close the door by pushing near the hinges!

By the time that they arrive in secondary school, all pupils have built up a wide experience of pushing and pulling objects to make them turn about some kind of pivot. For example, as young children play on a see-saw they shift around to make the beam balance without even thinking about it. If a young child finds it hard to open a door, you'll not see them making their next attempt by pushing closer to the hinge!

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