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Why did Leonhard Euler write Newton’s second law in the form F = ma?

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Title page of Isaac Newton's Philosophiae Naturalis Principia Mathematica, 1687, featuring large Latin text and publication details in a bordered layout. — 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.

The Swiss mathematician Leonhard Euler reformulated Newton’s second law of motion into the modern expression $F = m a$ in 1750.1

While Isaac Newton originally described the second law in terms of the time rate of change of momentum, Euler’s mathematical representation clarified the relationship between the variables involved. By writing the law as $F = m a$ , Euler made it explicitly clear that for a body with constant mass, the acceleration of the body is directly proportional to the force applied to it and inversely proportional to its mass. This formulation became a standard tool in physics for analyzing the motion of bodies.12