# Newton’s First Law of Motion

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Newton’s First Law of Motion

In what direction did the ship move? Why do you think so?
Krishna Gopal Shrivestava of India set an unofficial world record in 1999 by pulling a ship with a mass of 244,000 kg with his teeth. We can use this feat to learn about force, mass, and acceleration. How would a small rowboat be different if Shrivestava pulled it rather than a large ship? In what direction did the ship move? Why do you think so? When Shrivestava stopped pulling, did the ship stop moving? Explain. You may wish to locate a picture of this event and add it to this slide.

Famous Scientists The Laws of Motion
Great ideas on motion!

Section 1: The First Law of Motion
Objectives: Define Newton’s first law of motion. Explain how inertia and mass are related.

WRONG!! Aristotle (300 B.C.) Greece
His ideas were popular for ~2,000 years. Now, his ideas are obsolete. 2,000 years of false knowledge What Aristotle said: Heavier objects fall faster than lighter ones Earth is the center of the universe All motion on Earth is straight and linear WRONG!!

Aristotle (300 B.C.) Greece (cont.)
Aristotle’s ideas about motion were a beginning in scientific thought.

Galileo Galilei (1600’s) Italy
Discovered moons of Jupiter Supported the idea that planets revolve around the Sun Famous for ideas on motion…but these were not readily accepted in his time

Galileo Galilei (cont.)
Galileo’s Ideas on Motion: 1. All objects fall at same speed (independent of weight) 2. Introduced concept of friction- which slows things down 3. Inertia (sluggish or lazy)- tendency of an object to resist a change in its motion

Sir Isaac Newton (1700’s) England
“Father of Physics” Devised calculus Explained gravity, the universal law of gravitation (apple on head?) Formulated a theory on the nature of light Formulated the laws of motion

Newton’s 1st Law of Motion
An object at rest remains at rest… An object in motion maintains its velocity… Net force = 0 balanced forces, no acceleration! Unless it experiences an unbalanced force

First Law (cont.): INERTIA
Newton borrowed the idea from Galileo. The inertia of an object is the tendency of the object to resist a change in motion. The larger the mass of an object, the greater its inertia.

Newton’s 1st Law of Motion
Apply Newton’s 1st Law of motion to this picture:

Newton’s 1st Law of Motion
Sports Examples: A moving ball will keep moving forever. Unless slowed by external force of friction (ground, floor) or gravity A soccer ball in grass remains stationary. Until it is kicked (external unbalanced force)

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