Question 2 of 9702 Paper 3 tests a relationship with just two sets of readings, then asks what limited the experiment. By hand, move the lower clamp to stretch the band, read its ends against the rule and close the calipers on it. Calculate two values of k, decide whether they support the relationship, then choose limitations and the improvements that really fix them. Allow about 30 minutes.
Checked: Cambridge 9702 Paper 3, 2017 to 2019 and 2023 to 2025. Only the papers in our collection are listed, so the real number may be higher. Question papers are available from Cambridge.
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L₀ to the nearest millimetre with a sensible percentage uncertainty, widths from the calipers to 0.01 mm, two stretched lengths near 1.5 L₀ and 2 L₀, and k = w √L each time.
The percentage difference between your two values of k, and a conclusion that follows from it and the 20% criterion.
Two genuine limitations, each with the specific improvement that deals with it. Vague answers such as human error earn nothing.
The marking follows the conventions in published Cambridge mark schemes. The experiments, readings and wording on this page are our own.