The acceleration of an object is parallel and directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object.The object is either at rest and the velocity is zero or it moves in a straight line with a constant speed. If an object experiences no net force, its velocity will remain constant.The laws describe the relationship between forces acting on a body and the motions experienced due to these forces. Newton used these laws to explain and explore the motion of physical objects and systems. In 1687, he published a work called Philosophiae Naturalis Principla Mathematica, which described his three laws of motion. Sir Isaac Newton was an English scientist who was interested in the motion of objects under various conditions.