Forces in action
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7. Hooke´s law (2)


When Hooke’s law holds, the behaviour is linear; if shown on a graph, the line depicting force as a function of displacement should show a direct variation.

Hooke's Law states:

the extension is proportional to the force

• the spring will go back to its original length when the force is removed so long as we don't exceed the elastic limit.

• The elastic limit is where the graph departs from a straight line. If we go past it, the spring won't go back to its original length. When we remove the force, we're left with a permanent extension.

.• Below the elastic limit, we say that the spring is showing "elastic behaviour": the extension is proportional to the force, and it'll go back to it's original length when we remove the force.

Beyond the elastic limit, we say that it shows "plastic behaviour". This means that when a force is applied to deform the shape, it stays deformed when the force is removed.

• We use Hooke's Law in spring balances, kitchen scales and other devices where we measure using a spring.

• Small forces can be measured in a spring balance in units called newtons (N).

The simulation in bar menu will help you to understand Hooke´s Law.
You can also download the worksheet you can find in bar menu.

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