“I do not know what I may appear to the world, but to myself I seem to have been only like a boy playing on the sea-shore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.“ - Sir Isaac Newton -

Clicker Survey for Attendance Who is the best magician? –A Penn & Teller –B David Copperfield –C Harry Houdini –D David Blaine –E Criss Angel

Sir Isaac Newton (1643 – 1727) > Born shortly after Galileo died > Inventor of Calculus > Known for his laws of motion

Isaac Newton's own first edition copy of his Philosophiae Naturalis Principia Mathematica with his handwritten corrections for the second edition.

A reputed descendant of Newton's apple tree, found in the Botanic Gardens in Cambridge.

“If I have seen further it is by standing on the shoulders of giants”

Who are these giants?

Chapter 2 Newton’s First Law of Motion

Aristotle on Motion (350 BC) Aristotle attempted to understand motion by classifying motion as either (a) natural motion forces acting at a distance (b) or violent motion contact forces

“Large object tend to 'strive harder'.” He stated that “The Earth remains at rest.”

Geocentric Model - Earth Centered Universe

Copernicus (1500's) "The Earth and planets orbit the Sun.” He reasoned this from his astronomical observations.

Galileo (1600's) Scientist who supported Copernicus Dropped objects with different weights from the Leaning Tower of Pisa Found that all objects fall at the same rate if you can account for air resistance Pisa Pisa Moon

Friction - a force that resists motion e.g. air resistance and sliding on rough surfaces Inertia - the resistance of an object to change in its state of motion –“Sluggishness” Bow and Arrow Demo: Ball and incline plane

Galileo’s Incline Planes

Isaac Newton ( ) His three laws of motion first appeared in his book called Principia.

Newton’s First Law a.k.a “Law of Inertia” A body remains at rest or moves in a straight line at a constant speed unless acted upon by a force.

Newton’s First Law Examples Weight and string Card, cup, and coin Fixing a Hammer Demo - Coins on elbow Demo - Lead Brick and Hammer Demo - Table setting – Figure 2.4

Image from Isaac Newton's Principia (1687).

10 N NET FORCE A force or a combination of forces produces changes in motion (accelerations). 10 N m = 20 N m 10 N m = 0 N m 10 N m 20 N = m

THE EQUILIBRIUM RULE Examples of Mechanical Equilibrium: Hanging from a tree Weighing yourself on a set of scales Computer setting on a table Car parked on an incline Normal up Weight down Scales pushing up Tree pulling up Normal Friction

The Equilibrium Rule

Scales pushing up Weight down SUPPORT FORCE A table can supply an upward support force also known as a normal force. When we say “normal to” we are saying “at right angles to”. Normal up Weight down

Equilibrium is a state of no change. If an object moves in a straight line with no change in speed, it is in equilibrium. EQUILIBRIUM OF MOVING THINGS Examples: Driving at constant velocity Force from road Air Resistance Normal up Weight down Terminal velocity in parachuting Weight down Air resistance

It is hard to detect the motion of the earth because we are moving with it. Early science could not predict large enough forces to move the earth. Can Hewitt’s bird drop down and catch the worm if the Earth moves at 30 km/s? Demo - Cart and ball launcher Demo - Cart and ball launcher THE MOVING EARTH

Chapter 2 Review Questions

Which person below is most highly recognized for proposing a heliocentric universe? (a) Aristotle (b) Newton (c) Galileo (d) Copernicus

If an object weighs 10 lb, what must the air resistance force be if the object is falling and has reached terminal velocity? (a) 10 lb (b) 32 lb (c) there is no way of telling without knowing what the value of the terminal velocity is

Newton's concept of motion said that the natural state of an object was (a) constant velocity (b) constant acceleration (c) constant net force

Demonstrations for Chapter 2 Ball and incline plane Weight and string Card, cup, and coin Swinging Rocks Coins on elbow Table setting Bottle, hoop, and chalk Cart and ball launcher Lead Brick and Hammer

Chapter 3 Linear Motion See Homework 5