物理引擎是一个计算机进程模拟牛顿力学模型，使用质量、速度、摩擦力和空气阻力等变量。可以用来预测这种不同情况下的效果。它主要用在计算物理学和电子游戏以及电脑动画当中。

物理引擎有两种类型常见的型类：实时物理引擎和高精度物理引擎。高精度的物理引擎需要更多的处理能力来计算非常精确的物理，通常使用在科学研究（计算物理学）和电脑动画电影制作。实时物理引擎使用通常使用在电子游戏并且简化运算，降低精确度增以减少计算时间，得到在电子游戏当中可以接受的的处里速度。

A physics engine is computer software that provides an approximate simulation of certain physical systems, such as rigid body dynamics (including collision detection), soft body dynamics, and fluid dynamics, of use in the domains of computer graphics, video games and film. Their main uses are in video games (typically as middleware), in which case the simulations are in real-time. The term is sometimes used more generally to describe any software system for simulating physical phenomena, such as high-performance scientific simulation.