Forces in action _______________________________________________________________________________________________________________________________________________________________________________________________________________________
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. Figure 9.4
.• 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 the men baru.