Force–extension graphs
Read the axes first. On a force against extension graph, the gradient in the straight region is the spring constant. The area under the loading curve is the work done on the spring.
Specification outcomes (2)
- 3.4.1(d)(i) Interpret force–extension or compression graphs for springs and wires.
- 3.4.2(a) Interpret force–extension (or compression) graphs; calculate work done as area under graph.
H156 v2.0 · May 2026
See it in an exam
No exam example linked yet. You can still explore the explanation and related topics.
PhysicsUK practice
Questions are matched by their specification tags. Read the prompt to check how it relates to this topic; use “Report tag issue” if a match seems wrong.
A technician calibrates the spring bumper of a small instrument trolley. Figure 1 shows the force F needed to compress the spring by x from its natural length. The graph is a straight line through (0, 0), (0.020 m, 1.2 N), (0.040 m, 2.4 N) and (0.060 m, 3.6 N). The trolley has mass 0.60 kg. It is released from rest against the spring at compression 0.060 m on a horizontal track. A constant resistive force of 0.60 N opposes the motion as soon as the trolley moves. The spring's mass is negligible and its deformation is elastic. The trolley loses contact with the spring at its natural length. There are no other energy losses. (a) Use the gradient of the force-compression graph to determine the spring constant. [2] (b) Use the graph to calculate the work needed to compress the spring from its natural length to 0.060 m. [2] (c) Calculate the acceleration just after release, stating its direction relative to the bumper. [3] (d) Calculate the speed when the trolley loses contact with the spring. Account for the work done against resistance. [3] (e) Explain why a single constant-acceleration equation cannot describe the whole interval while the trolley is in contact with the spring. [2] (f) Calculate the distance travelled after losing contact before the trolley stops. Use a constant-acceleration equation for this part. [3]
Matched by specification tags · 15 marks
Try this question now →