Newton

1
Newtons Laws of Motion

• Chapters 3,6,7

2
Physics

• Kinematics
• Deals with how objects move
• Displacement, velocity, acceleration
• Dynamics
• Deals with why objects move
• Newtons Laws of Motion
• Forces, weight/mass, Friction

3
Newtons 1st Law (N1L)

• Law of Inertia
• An object at rest will stay at rest, an object in
  motion will remain in motion at the same speed
  and in a straight line path, unless acted upon by
  an outside force.

4
Newtons 2nd Law (N2L)

• The acceleration of an object is
• Directly proportional to the net force acting on
  it
• Inversely proportional to its mass
• In the same direction as the applied unbalanced
  force

5
Newtons 2nd Law (N2L)

• F ma
• F Net Force
• m mass
• a acceleration
• Units Force Newton(N) kgm/s2

6
Newtons 3rd Law (N3L)

• When an object exerts a force on a second object,
  the second object exerts a force on the first
  object that is equal in magnitude and opposite in
  direction
• Must be two objects acting on each other
• Forces occur in Action/Reaction pairs

7
N3L Example

• A Chandelier hanging from a ceiling

Wire pulls up on chandelier
Chandelier pulls down on wire
8
N3L Example
9
N3L Example
10
N3L Example
Action Man pushes stroller
Reaction Stroller pushes man
11
(No Transcript)
12
Mass vs. Weight

• Mass Amount of matter in an object
• Never changes
• Weight (w or Fg) Force due to gravity
• Changes with location
• w mg
• weight is a force, measured in Newtons(N)

13
Weight, w

• Force due to gravity, Fg

14
Normal Force, N or FN

• Force exerted by a surface whenever an object is
  in contact with a surface
• Normal force is always perpendicular to the
  surface

15
Concurrent Forces

• Two concurrent forces acting on an object..
• Two forces acting concurrently
• Means the forces are acting on the same object at
  the same time

16
Force Diagrams

• All forces acting on an object are drawn as
  arrows, originating from the object, pointed
  outward from the object

FN
Fg
17
(No Transcript)
18
Friction, f or Ff

• Slowing Force
• Force that opposes motion as a result of contact
  between surfaces.
• Always in the direction opposite to motion
• Direction is always parallel to the surface

Friction
v
19
Normal Force, N or FN

• Normal force is always perpendicular to the
  surface

FN
Ff
v
20
Coefficient of Friction

• Defined as the ration of frictional force to
  normal force

21
Static Friction

• Starting Friction
• Force that opposes the START of an object moving
• When an object is at rest, the object will not
  move until the applied force is greater than the
  maximum force of static friction

22
Kinetic Friction

• Also called sliding friction
• Friction that results when objects slide past one
  another
• Static Friction is greater than kinetic friction
• NOT dependent on surface area or velocity

23
Coefficient of Friction,µ