ARISTOTLES CLASSIFICATION OF MOTION

• Aristotle classified motion into two kinds
• Natural and unatural motion

Galileo's concept of interia

• Galileos said that force is required to start an object moving,but once moving,no force is required to keep it moving-except for the force needed to overcome friction

GALILEO'S CONCEPT OF SPEED AND VELOCITY

• Speed is distance covered per unit of time
• Speed=distance/time
• When we know both speed and direction of an object, we know its velocity
• Speed is a discription of how fast;velocity is how fast and in what direction
• A quantity such as velocity specifies direction as well as magnitude is called VECTOR QUANTITY

MOTION IS RELATIVE

NEWTON'S FISRT LAW OF MOTION--THE LAW OF INERTIA