Movement is represented by these numbers changing over time: a body's trajectory is represented by a function that assigns to each value of a time variable the values of all the position coordinates. The mathematical description of motion, or kinematics, is based on the idea of specifying positions using numerical coordinates. For instance, the Earth and the Sun can both be approximated as pointlike when considering the orbit of the former around the latter, but the Earth is not pointlike when considering activities on its surface. This is a reasonable approximation for real bodies when the motion of internal parts can be neglected, and when the separation between bodies is much larger than the size of each. Newton's laws are often stated in terms of point or particle masses, that is, bodies whose volume is negligible. 9.4 Momentum conservation and the third law.8.1 Thermodynamics and statistical physics.7 Relation to other formulations of classical physics.5.2 Rotational analogues of Newton's laws.Limitations to Newton's laws have also been discovered: new theories are necessary when objects are very fast ( special relativity), very massive ( general relativity), or very small ( quantum mechanics). In the time since Newton, the conceptual content of classical physics has been reformulated in alternative ways, involving different mathematical approaches that have yielded insights which were obscured in the original, Newtonian formulation. Newton used them to investigate and explain the motion of many physical objects and systems, which laid the foundation for classical mechanics. The three laws of motion were first stated by Isaac Newton in his Philosophiæ Naturalis Principia Mathematica ( Mathematical Principles of Natural Philosophy), originally published in 1687. If two bodies exert forces on each other, these forces have the same magnitude but opposite directions.When a body is acted upon by a force, the time rate of change of its momentum equals the force.A body remains at rest, or in motion at a constant speed in a straight line, unless acted upon by a force.These laws can be paraphrased as follows: : 49 Newton's laws of motion are three basic laws of classical mechanics that describe the relationship between the motion of an object and the forces acting on it.

Three laws in physics science