Newton’s 1 st Law of Motion by: Heather Britton

Newton’s 1 st Law of Motion We have learned what happens to an object once it is set in motion Now we will study what causes objects to change their state of being Dynamics - the connection between motion and force, or why objects move

Newton’s 1 st Law of Motion Force - a push or pull Force is a vector quantity (has both magnitude and direction) and can therefore be added like velocity See notes on addition of vectors for a review

Newton’s 1 st Law of Motion Aristotle was one of the first scientists of record to study how motion happens There was natural motion which was vertical motion rocks falling smoke rising

Newton’s 1 st Law of Motion There was also violent motion or imposed motion Violent motion must be caused by a continuous external force throwing an object leaves blown along the ground

Newton’s 1 st Law of Motion This was the best explanation we had for 2,000 years Then along came Galileo in the early 1600’s who questioned Aristotle’s views on motion

Newton’s 1 st Law of Motion Galileo came to a different conclusion after many experiments Objects are just as likely to move with constant velocity as they were to be at rest

Newton’s 1 st Law of Motion The year Galileo died Sir Isaac Newton was born Newton continued Galileo’s work and provided us with three laws concerning motion He published these in his book Principia in 1687

Newton’s 1 st Law of Motion Newton’s First Law of Motion states Every body continues in its state of rest or of uniform speed in a straight line unless acted on by a non-zero net force

Newton’s 1 st Law of Motion Net force - the sum of all forces Remember when adding forces the directions must be taken into account The direction of the net force effects the movement of the object

Newton’s 1 st Law of Motion Inertia - the tendency for a body to keep doing what it is doing Newton’s first law of motion is also called Newton’s law of inertia objects at rest stay at rest objects in motion stay in motion

Newton’s 1 st Law of Motion Equilibrium - when the net force exerted on an object is zero When an object is in equilibrium it does not mean there are no forces exerted on it Equilibrium means all the forces are balanced or even