A student investigates the stretching of a spring. The student suspends the spring from the clamp of a retort stand as shown in Fig. 3.1. [Figure 3.1]

1. (a)(i)On Fig. 3.2, take readings from the metre rule level with the top of the spring and level with the bottom of the spring. Do not include the loops at the top and the bottom of the spring in your measurements. Record your readings to the nearest 0.1 cm. [Figure 3.2] reading level with top of spring = .............................................. cm reading level with bottom of spring = .............................................. cm [2][2]
2. (a)(ii)Draw on Fig. 3.2 to show how the student uses a set-square to take a reading from the metre rule level with the bottom of the spring. [1][1]
3. (b)(i)Calculate the length l of the coiled part of the spring. Use the equation shown. l = reading level with bottom of spring – reading level with top of spring Show your working. Record l in Table 3.1 on page 12 for a load L = 0.0N. [1][1]
4. (b)(ii)The student: • places a load L = 1.0 N on the spring • takes readings to determine the new length l of the spring. The top of the spring does not move but the bottom of the spring moves downwards. The student determines that the new reading on the rule level with the bottom of spring is 45.2 cm. Calculate the new length l of the spring. Record your answer for the new length l for a load L = 1.0N in Table 3.1 on page 12. [1][1]
5. (c)The student repeats the procedure in (b)(ii) for loads L = 2.0N, 3.0N, 4.0N and 5.0N. The results are shown in Table 3.1. Table 3.1 load L/N | 0 | 1.0 | 2.0 | 3.0 | 4.0 | 5.0 length l/cm | | | 10.0 | 14.0 | 18.2 | 21.9 On the grid provided in Fig. 3.3 on page 13, plot a graph of l on the y-axis against L on the x-axis. Start from the origin (0, 0). Draw the straight line of best fit. [4][4]
6. (d)Use the data in Table 3.1 and the graph in Fig. 3.3 to determine the extension of the spring when a load of 3.5N is added to the spring. Show your working. extension = .............................................. cm [2][2]
7. (e)A student suggests that the stretched length l of the spring is proportional to load L. State if the data in Table 3.1 supports this suggestion. Justify your statement using the data in Table 3.1 or the graph in Fig. 3.3. statement ............................................................................................................................................................................................................................................ justification ............................................................................................................................................................................................................................................ [1][1]
8. (f)Line of sight (parallax) errors can occur when readings are taken from the metre rule. State one practical technique, other than using a set square, that ensures accurate readings are taken from a metre rule. [1][1]
9. (g)The student repeats the procedure described in (c) two more times and averages the readings before calculating the spring lengths l for each load L. Explain why the student does this. [1][1]

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