For fixed impulse j , the equation suggests that t 1 → → t 0 ⇒ ⇒ | f | → → ∞ ∞ , that is, a smaller time interval must be compensated by a stronger reaction force to achieve the same impulse. When modelling a collision between idealized rigid bodies, it is impractical to simulate the compression and expansion phases of the body geometry over the collision time interval. However, by assuming that a force f can be found which is equal to 0 everywhere except at t 0 , and such that the limit