Springs

Springs are important to build realistic objects. In the real world, we use springs everywhere, from watches to the suspension of cars. In games, we can use springs to model these same interactions, or to simulate more complex systems, such as rigidbodies.

Every spring has a Resting Length, sometimes called the spring's Equilibrium. Equilibrium describes the length of a resting spring, that is, when the spring is not contracted or stretched. When a spring is contracted or stretched away from its equilibrium, the spring will try to pull back to its resting length with a force equivalent to the difference of its current length and resting length. This describes Hooke's Law. Mathematically, Hooke's Law is expressed by the following equation:

In this equation, F is the force exerted by the spring, k is the spring constant, and x is the difference between the current length and resting length of the spring. The spring constant represents the strength of the spring, that is, how stiff or...