physical half-life

例句：

1. 1.The scientist's theory is based on physical principles.
   科学家的理论基于物理原理。
2. 2.The physics teacher explained the concept of gravity in a simple way.
   物理老师用简单的方式解释了重力的概念。
3. 3. The material was found to be physically strong and durable.
   这种材料被发现具有物理强度和耐用性。