"N.__'s first law of motion:  An object moves with a velocity that is constant in magnitude and direction, unless acted on by a nonzero force.  [...]  N__'s second law:  The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass.  [...]  N__'s law of universal gravitation:  Every particle in the universe attracts every other particle with a force that is directly proportional to the product of the masses of the particles and inversely proportional to the square of the distance between them.”—Thank you, Raymond A. Serway, Chris Vuille, & Jerry S. Faughn, for College Physics, Volume 1, Eighth Edition, Thomson Higher Education, 2008, pp.85,86,90.  Thank you, Ken Cropper, M.D., for access to the library from which this book was borrowed.  *Isaac Newton.