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“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
–B
–C
–D
–E
Penn & Teller
David Copperfield
Harry Houdini
David Blaine
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


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 Planes
Isaac Newton (1642-1727)
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
Figure 2.4
Fixing a Hammer
Demo - Coins on elbow
Demo - Lead Brick and Hammer
Demo - Table setting
–
http://www.youtube.com/watch?v=T9KPwNeCdSg
Image from Isaac Newton's Principia (1687).
NET FORCE
 A force or a combination of forces
produces changes in motion
(accelerations).
10 N
10 N
10 N
20 N
m
=
m
10 N
=
m
10 N
=
m
20 N
0N
10 N
m
m
THE EQUILIBRIUM RULE
Examples of
Mechanical
Equilibrium:
Computer setting on a table
Scales pushing up
Normal up
Weight down
Weighing yourself on a set of scales
Hanging from a tree
Car parked on an incline
Friction
Tree
pulling up
Weight down
Normal
Weight down
Weight down
The Equilibrium Rule
F

0

Normal up
SUPPORT FORCE
A table can supply an
upward support force
also known as a
normal force.
Weight down
Scales pushing up
When we say
“normal to”
we are saying
“at right angles to”.
Weight down
EQUILIBRIUM OF MOVING THINGS
 Equilibrium is a state of no change.
 If an object moves in a straight line with no
change in speed, it is in equilibrium.
Examples:
Driving at constant velocity
Normal up
Air resistance
Force from road
Air
Resistance
Weight down
Terminal velocity in parachuting
Weight down
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
Chapter 3
Linear Motion
See Homework 5