2 Aristotle (4th Century,BC) Motion: Natural Motion (Objects would seek their natural resting places, thought not to be caused by forces)Violent Motion ( Imposed motion, it had an external cause )Copernicus ( )Formulated his theory of the moving EarthGalileo (1564 – 1642)Demolished the notion that a force is necessary to keep an object moving. Force: Any push or Pull Friction: Force that act between materials that touch as they move Inertia: Property of a body to resist change
3 Newton’s Law of Inertia Every object continues in a state of rest, or of motion in a straight line at a constant speed, unless it is compelled to change that state by forces exerted upon it.
4 Mass – A measure of Inertia Mass is not a Volume Volume is a measure of space (cm3, m3, liters)Mass is not a Weight Mass is the quantity of matter in an object (kg) Weight is the force of gravity on an objectMass and Weight are proportional to each other, but they are not equal to each otherWeight = mass x acceleration due to gravity Weight = m ∙ gThe SI unit of force (weight) is Newton
5 Net Force : The combination of all forces acting on an object is called net force. In the absence of a net force, objects do not change their state of motionEquilibrium: When Net Force equals Zero