Newton ’ s Laws of Motion

The Man Behind the Laws  His mom wanted him to be a farmer.  He was motivated at school by trying to be smarter than a bully.  His college closed for a while because of the plague, and, while on break, discovered and wrote the law of gravity.  He discovered calculus and even invented the reflective telescope (he ’ d also stare at the sun until he would lose his vision).  There really was an apple tree — but the apple probably didn ’ t hit him in the head. He wondered why the apple always fell in a straight line and applied the idea to the moon

The 3 Laws  The law of inertia  The law of acceleration  The law of equal and opposite forces  The laws are universal.  Apply to planets and peas

First Law: The law of inertia  An object at rest remains at rest, and an object in motion remains in motion at a constant speed and in a straight line unless acted on by an unbalanced force  Friction is an unbalanced force  Inertia means resisting change in motion

Second Law: The law of acceleration  The acceleration of an object depends on the object ’ s mass and the force applied to it  A=f/m F=ma  Explains why objects fall with same acceleration (10N=1kg)

Third Law: Equal and Opposite  Whenever one object exerts a force on a second object, the second object exerts an equal and opposite force on the first  Forces act in pairs  Action and reaction forces act on different objects

The Laws at Work