| English | Spring constant |
|---|---|
| Bahasa Melayu | Pemalar spring |
| 中文 | 弹簧常数 |
Definition
The force needed to produce unit extension in a spring, a measure of its stiffness; measured in newtons per metre (N m⁻¹).
In exam terms
The spring constant, k, is the force needed to produce unit extension in a spring, and it measures how stiff the spring is. From Hooke's law it is k = F ÷ x, so its unit is newtons per metre (N m⁻¹).
A large spring constant means a stiff spring that extends only a little for a given force; a small one means a soft spring.
For example, if a spring extends by 0.030 m under a force of 6.0 N, its spring constant is k = 6.0 N ÷ 0.030 m = 200 N m⁻¹. On a force–extension graph, k is the gradient of the straight-line region.
Don't confuse it with extension
Do not confuse the spring constant with the extension. The spring constant is a fixed property of the spring in N m⁻¹, while the extension in metres changes with the force applied.
It is also not the elastic potential energy stored, which is measured in joules (J).
In Paper 2 this is usually asked with 'Calculate the spring constant' or 'Compare the stiffness…', often by taking the gradient of a force–extension graph. Show the division with units so the answer comes out in N m⁻¹.
Source: DSKP KSSM Physics Form 4 and 5 (Versi English) (Bahagian Pembangunan Kurikulum (BPK), KPM)