Newton

1
Newtons Laws

• The Study of Dynamics

2
Isaac Newton

• Arguably the greatest scientific genius ever.
• Came up with 3 Laws of Motion to explain the
  observations and analyses of Galileo and Johannes
  Kepler.
• Discovered that white light was composed of many
  colors all mixed together.
• Invented new mathematical techniques such as
  calculus and binomial expansion theorem in his
  study of physics.
• Published his Laws in 1687 in the book
  Mathematical Principles of Natural Philosophy.

3
What is a Force?

• NO not THE Force
• A force is a push or pull on an object. It may
  be from gravity, electrical, magnetic, or muscle
  efforts.

http//members.aol.com/PrinceG0R0/jedi.html
4

• Contact Forces Field Forces
• Arise because of direct Gravity
• contact between objects. Electric
  Act over a distance.
• ex friction, tension Magnetic

5

• A net force causes an object to accelerate
• To speed up
• To slow down
• To change direction

6
External Forces

• An external force is a force that acts on an
  object due to its environment.
• The net external force is the (vector) sum of all
  the forces acting on the body.

7
Newtons First Law

• A body in motion stays in motion at constant
  velocity and a body at rest stays at rest unless
  acted upon by a net external force.
• This law is commonly referred to as the Law of
  Inertia.

8
Inertia

• Inertia is the tendency of an object to maintain
  its state of motion.
• The inertia of an object is proportional to its
  mass.
• Ex. A basketball in motion has more inertia than
  a tennis ball in motion.

9
Inertia

• Newtons First Law explains inertia because when
  there are no unbalanced forces acting upon an
  object, the object will preserve its state of
  motion.
• Ex. A ball at rest on the ground doesnt
  spontaneously move.

10
Ex Newtons 1st Law of Motion
The small car acts (applies force) against the
truck. Since the ladder was not latched, it had
no other force acting on it, and it kept going

• http//www.geocities.com/Athens/Academy/9208/il.ht
  ml

11
Implications of Newtons 1st Law

• If there is zero net force on a body, it cannot
  accelerate, and therefore must move at constant
  velocity, which means
• it cannot turn,
• it cannot speed up,
• it cannot slow down.

12
What is Zero Net Force?
Physics
A book rests on a table.
Even though there are forces on the book, they
are balanced. Therefore, there is no net force on
the book. SF 0
13
Equilibrium

• An object is in equilibrium when the net external
  forces are zero.
• Objects that are either at rest or have a
  constant velocity are in equilibrium.

14
Free body diagram (FBD)

• Shows all the forces acting on an object.
• support force
• friction force Applied
  force
• weight

15
Diagrams

• Draw a force diagram and a free body diagram for
  a book sitting on a table.