Newtons laws

Newton's first law of motion

If no external force acts on a particle, then it is possible to select a set of reference frames, called inertial reference frames, observed from which the particle moves without any change in velocity.

In Latin

Lex I: Corpus omne perseverare in statu suo quiescendi vel movendi uniformiter in directum, nisi quatenus a viribus impressis cogitur statum illum mutare. Principia Mathematica.

Newton's second law of motion

$\left.F\right.=ma$

Where $F$ is the force, $m$ is the mass and $a$ is the acceleration. This law has been found to be true for accelerations as small as $5\times 10^{-14}m/s^{2}$ (Ref. 2)

In Latin

Lex II: Mutationem motus proportionalem esse vi motrici impressae, et fieri secundum lineam rectam qua vis illa imprimitur. Principia Mathematica.

Interesting reading

• Frank Wilczek "Whence the Force of F = ma? I: Culture Shock", Physics Today October pp. 11-12 (2004)
• Frank Wilczek "Whence the Force of F = ma? II: Rationalizations", Physics Today December pp. 10-11 (2004)
• Frank Wilczek "Whence the Force of F = ma? III: Cultural Diversity", Physics Today July pp. 10-11 (2005)

References

• Adrian Cho "No Twisting Out of Newton's Law", ScienceNOW Daily News 13 April 2007
• J. H. Gundlach, S. Schlamminger, C. D. Spitzer, K.-Y. Choi, B. A. Woodahl, J. J. Coy, and E. Fischbach "Laboratory test of Newton's second law for small accelerations", Physical Review Letters 98 150801 (2007)

Newton's third law of motion

Whenever A exerts a force on B, B simultaneously exerts a force on A with the same magnitude in the opposite direction.

In Latin

Lex III: Actioni contrariam semper et æqualem esse reactionem: sive corporum duorum actiones in se mutuo semper esse æquales et in partes contrarias dirigi. Principia Mathematica.

Interesting reading

• A. V. Ivlev, J. Bartnick, M. Heinen, C.-R. Du, V. Nosenko, and H. Löwen "Statistical Mechanics where Newton’s Third Law is Broken", Physical Review X 5 011035 (2015)