Transcript Expectations for Ch 2 & 3

Physics Topics
• I. MECHANICS
• II. WAVES AND OPTICS
• III. ELECTRICITY AND MAGNETISM
• IV. MODERN PHYSICS
• V. ASTRONOMY
Thinking Back…
• What were some of the tools of a
Physicist?
Thinking Back…
• What were some of the tools of a
Physicist?
Practice safety & ethics
Identify & describe equipment
Use SI System
Manipulate formulas
The Scientific Method
Use Lab Report Format
What do you know?
• What is a frame of reference?
What do you know?
• What is a frame of reference?
• A system to determine location or motion
of an object.
• How can I tell if something is moving and
how fast?
What is acceleration?
What is acceleration?
• Rate of change of speed
• Occurs when we fall or go around a corner
What are forces and how do they
commonly occur?
What are forces and how do they
commonly occur?
• A force is a push or a pull
• They commonly occur in pairs
What are Newton’s Laws of Motion?
What are Newton’s Laws of Motion?
• #1 Inertia
• #2 F = ma
• #3 Action/Reaction
Motion I
Motion in One Dimension Quantities, Units, Speed, Position,
Distance, Displacement, Velocity,
Vector, Scalar, etc.
Assignment
• Read Chapter 2
• After reading the chapter, complete your
Reflections on the chapter.
What you need to know
¤ Motion can be
described and
analyzed in several
ways
¤ How coordinate
systems can be used
in motion studies
¤ Terms such as
displacement,
magnitude, vectors
¤ More Terms: scalars,
resultant vectors
¤ Interpret motion
graphs
¤ Attributes of
coordinate system origin & axis
¤ Models of motion
diagrams
Also Needed to Know
¤ Speed, distance (d),
¤ The slope of the
and time are scalar
distance-time graph is
quantities.
velocity.
¤ Velocity, displacement ¤ The slope of the
(s), force and
velocity-time graph is
acceleration are
acceleration.
vectors.
possibilities
•
•
•
•
Object not moving, v = 0 m/s
Object moving at constant velocity
Object accelerating
Object decelerating (negative
acceleration)
• (Last 2 situations have unbalanced forces
acting on them - to be discussed later in
the book)
Organizing your thoughts
(and units)
• Fundamental
Quantities
– Length
– Mass
– Time
• Derived Quantities
– Velocity
– Density
– Volume
• Fundamental Units
– Meter
– Kg
– Sec
• Derived Units
– m/s
– g/ml or g/cm3
– m3 or cm3
The "Big Five"
Kinematics
Equations
Constant
acceleration is
assumed
Average Speed/Velocity
Defined
v = d / t = ½(Vf + Vo)
Average Acceleration Defined
a = ∆v / ∆t = (Vf - Vo) / (tf - to)
Final Velocity of an Accelerating
Body
Distance Traveled by an
Accelerating Body
What can I do if I don't know the
time interval?
Vf = Vo + a(∆t)
d = Vo(∆t) + ½ a(∆t)2
Vf2 - Vo2 = 2 a d
In the above formulas,
a can be replaced with g
g = 9.8 m/s2
(acceleration on Earth due to gravity when an
object is falling)
Equation of motion for average velocity:
d = vt + di
Online Notes
• http://www.physicsclassroom.com/Default2
.html
• This site has information which may be
helpful to you in your basic study of
Physics.
Scalars & Vectors
• Scalars have magnitude only (a number with
units) such as a length of 5.0 m or a speed
of 29.3 m/s
• Vectors have magnitude and direction
– Velocity: 29.3 m/s North
– Force: 25 newtons South
– Displacement
Vectors
• Are represented by an arrow
• Length drawn to a chosen scale
(1cm:50m/s)
• Direction N
S
E
W
• Vector addition:
– Same direction: add
– Opposite directions: subtract
Adding Vectors
A
B
R
A+BR
A
B
R
A + (-B)  R