“i do not know what i may appear to the world, but to myself i seem to have been only like a boy...

“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 AttendanceWho 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 Who are these giants?giants?

Chapter 2Chapter 2Newton’s First Newton’s First Law of MotionLaw of Motion

Aristotle on Motion Aristotle on Motion (350 BC)(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)Copernicus (1500's)

"The Earth and planets orbit the Sun.”

He reasoned this from his astronomical observations.

Galileo (1600's)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

http://www.youtube.com/watch?v=YD6JYdKxRjo Pisa http://www.youtube.com/watch?v=x7dUgiKzLSc Pisa http://www.youtube.com/watch?v=WOvwwO-l4ps 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”

http://www.youtube.com/watch?v=w3Vhz9b6iKg Bow and Arrow

Demo: Ball and incline plane

Galileo’s Incline PlanesGalileo’s Incline Planes

Isaac Newton (1642-1727)Isaac Newton (1642-1727)

His three laws of motion first appeared in his book called Principia.

Newton’s First LawNewton’s First Lawa.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 ExamplesWeight and string

Card, cup, and coin

Fixing a Hammer

Demo - Coins on elbowDemo - Lead Brick and HammerDemo - Table setting

– http://www.youtube.com/watch?v=T9KPwNeCdSg

Figure 2.4

Image from Isaac Newton's Principia (1687).

10 N

NET FORCEA force or a combination of forces

produces changes in motion (accelerations).

10 N m10 N

= 20 N m

10 Nm10 N = 0 N m

10 Nm20 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

Weight down

Weight downWeight down

Scales pushing up

Tree pulling up

NormalFriction

The Equilibrium Rule

0F

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

AirResistance

Normal up

Weight down

Terminal velocity in parachuting

Weight down

Air resistance

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 If an object weighs 10 lb, what must the air resistance force be if the object is falling resistance force be if the object is falling and has reached terminal velocity?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

Chapter 3Chapter 3

Linear MotionLinear MotionSee Homework 5See Homework 5