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When do Newton’s laws give an accurate description of motion?
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Newton’s laws of motion
The title page of Isaac Newton's Philosophiae Naturalis Principia Mathematica (1687; Mathematical Principles of Natural Philosophy), the work in which the physicist introduced his three laws of motion.
Newton’s laws of motion provide an accurate description of nature for most macroscopic objects moving at speeds significantly slower than the speed of light.21
While these laws serve as the foundation of classical mechanics, they are not the most fundamental laws of physics. Their accuracy is limited in the following contexts:
- High Speeds: When objects move at velocities approaching the speed of light, Newtonian mechanics breaks down and must be replaced by relativistic mechanics.23
- Microscopic Scales: For very small bodies, such as electrons or other subatomic particles, quantum mechanics provides the necessary framework for describing motion.24
In essence, modern theories like relativity and quantum mechanics reduce to Newton’s laws when applied to larger bodies or those moving at slower, everyday speeds.2