HOOKE'S LAW
4 marks · EasyA student investigates how a metal spring stretches when forces are applied. The table below shows her results.
| Force / N | Length / cm |
|---|---|
| 0 | 4.5 |
| 2 | 5.1 |
| 4 | 5.7 |
| 6 | 6.3 |
| 8 | 6.9 |
Calculate the extension of the spring for each force value. Complete the table below.
| Force / N | Extension / cm |
|---|---|
| 0 | |
| 2 | |
| 4 | |
| 6 | |
| 8 |
What was the original (unstretched) length of the spring?
Does this spring obey Hooke's law in the range shown? Give a reason for your answer.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
Show answer
(a) —
(b) 4.5 cm
(c) Yes, the extension increases evenly with force (proportional relationship: straight line).
Show mark scheme and worked solution
Marking points
M1 (a) · 1 mark · Correct method for finding extension (subtract original length from each measurement).
A1 (a) · 1 mark · All extension values correct for all rows.
B1 (b) · 1 mark · Correctly identifies unstretched length as 4.5 cm.
B2 (c) · 1 mark · Correct conclusion and supporting reason (e.g., straight line/proportional).
Worked solution
a) Extension = (measured length) - (original length)
| Force / N | Extension / cm |
|---|---|
| 0 | 0.0 |
| 2 | 0.6 |
| 4 | 1.2 |
| 6 | 1.8 |
| 8 | 2.4 |
b) The original length is the length with zero force: 4.5 cm.
c) Yes, the extension values increase by 0.6 cm for each 2 N step — this shows direct proportionality (a straight-line relationship).