Why does the apple just fall in a straight line and not an angle?
Newton was sitting under an apple tree when a fruit fell and hit him on the head, inspiring him to suddenly come up with the theory of gravity. While there is no evidence that the apple actually hit Newton on the head, he did see an apple fall from a tree, leading him to wonder why it fell straight down and not at an angle.
Newton published Philosophiae Naturalis Principia Mathematica. It explains the laws of physics. - A stationary body will stay stationary unless an external force is applied to it. - Force is equal to mass times acceleration, - For every action, there is an equal and opposite reaction.
Newton's first major public scientific achievement was designing and constructing a reflecting telescope in 1668. As a professor at Cambridge, Newton was required to deliver an annual course of lectures and chose optics as his initial topic. He used his telescope to study optics and help prove his theory of light and color.