The table below shows measurements from tests on a bungee cord used to lower equipment boxes from a platform. Fig. 1 shows how the extension was measured be...
Question 1 Report
The table below shows measurements from tests on a bungee cord used to lower equipment boxes from a platform. Fig. 1 shows how the extension was measured beside a metre rule. The same cord was used in every test and the student allowed it to stop moving before recording each result.
| load / N | extension / cm |
|---|---|
| 20 | 6.0 |
| 40 | 12.0 |
| 60 | 18.0 |
| 80 | 31.0 |
(a) State the extension produced by a 60 N load. [1]
(b) Describe the relationship between load and extension up to 60 N. [1]
(c) Explain what the 80 N result suggests about the cord. [2]
Answer Details
(a) From the table, a 60 N load produces an extension of 18.0 cm. [1]
(b) Up to 60 N, doubling the load doubles the extension, so extension is directly proportional to load. [1]
(c) If proportionality continued, an 80 N load would give \(24.0\,\text{cm}\), but the measured extension is 31.0 cm. Therefore extension is no longer proportional to force. The limit of proportionality has been exceeded; the cord may also have been permanently stretched. [2]
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