定律 (dìng lǜ): กฎหมายทางวิทยาศาสตร์ (เช่น กฎหมายอนุรักษ์พลังงาน)

Newton's law of universal gravitation can not only explain why an apple falls to the ground, but also calculate the orbits of planets around the sun.

In physics class, the teacher demonstrated the law of conservation of energy to the students through an experiment: energy can neither be created nor destroyed out of nothing.

According to the second law of thermodynamics, heat always spontaneously transfers from a hot object to a cold object, and cannot go the other way around.

By observing planetary motion, Kepler summarized the three laws of planetary motion, laying the foundation for Newton's later discovery of the law of universal gravitation.