spring constant

The spring constant, often symbolized as *k*, measures how stiff a spring is. It indicates the amount of force needed to stretch or compress the spring by a certain distance. A higher spring constant means the spring is stiffer — it requires more force to produce a given stretch or compression. Conversely, a lower spring constant means the spring is more flexible and easier to deform. Essentially, *k* tells you the spring's resistance to being stretched or compressed, which is useful in understanding how springs behave under applied forces.