HOOKE'S LAW
2 marks · EasyExplain how you would check if a metal wire obeys Hooke’s law in a laboratory experiment.
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Measure the original length of the wire, then add weights one by one, measuring the new length each time. Find the extension for each force, plot a graph of force against extension, and look for a straight line through the origin. If so, the wire obeys Hooke's law.
Also accept: Record force and extension and plot force against extension; check for direct proportionality (straight line through origin).
Common mistakes: Forgetting to mention graphing the results.
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Marking points
B1 · 1 mark · Describes measuring original length, applying forces stepwise, and measuring extension for each force.
B2 · 1 mark · Describes plotting graph and verifying proportionality (straight line through origin) to check if it obeys Hooke’s law.
Worked solution
First, measure the original length of the wire. Then, add weights one at a time, measuring the new length each time. For each weight, calculate extension. Plot a graph of force (y-axis) against extension (x-axis). If the graph is a straight line through the origin, the wire obeys Hooke’s law.