physics intro & kinematics
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PHYSICS INTRO & KINEMATICS
•Quantities
•Units
•Vectors
•Displacement
•Velocity
•Acceleration
•Kinematics
•Graphing Motion in 1-D
QUANTUM
MECHANICS
QUANTUM
FIELD THEORY
CLASSICAL
MECHANICS
RELATIVISTIC
MECHANICS
Near or less
than 10-9m
Far larger
than 10-9m
Far less
than 3 x108 m/s
Near 3 x108 m/s
Near or less
than 10-9m
SOME PHYSICS QUANTITIES
Vector - quantity with both magnitude (size) and direction
Scalar - quantity with magnitude only
Vectors:
• Displacement
• Velocity
• Acceleration
• Momentum
• Force
Scalars:
• Distance
• Speed
• Time
• Mass
• Energy
MASS VS. WEIGHT
On the moon, your mass would be the same,
but the magnitude of your weight would be less.
Mass
• Scalar (no direction)
• Measures the amount of matter in an object
Weight
• Vector (points toward center of Earth)
• Force of gravity on an object
VECTORS
• The length of the arrow represents the magnitude (how far, how fast, how strong, etc, depending on the type of vector).
• The arrow points in the directions of the force, motion, displacement, etc. It is often specified by an angle.
Vectors are represented with arrows
42°
5 m/s
More on Vectors
Later in the Course
UNITS
Quantity . . . Unit (symbol)
• Displacement & Distance . . . meter (m)
• Time . . . second (s)
• Velocity & Speed . . . (m/s)
• Acceleration . . . (m/s2)
• Mass . . . kilogram (kg)
• Momentum . . . (kg·m/s)
• Force . . .Newton (N)
• Energy . . . Joule (J)
Units are not the same as quantities!
UNITS
Quantity . . . Unit (symbol)
•Volt (V)………….Volt (V)
Units are not the same as quantities…
EXCEPT FOR
SI PREFIXES
pico p 10-12
nano n 10-9
micro µ 10-6
milli m 10-3
centi c 10-2
kilo k 103
mega M 106
giga G 109
tera T 1012
Small Scale Large Scale
You are required to know nano through Giga
Course ContentKinematics in One and Two Dimensions
Dynamics: Newton’s Laws
Circular Motion and
Universal Law of Gravitation
Energy and Conservation of Energy
Impulse and Momentum
Conservation of Momentum: Collisions
Simple Harmonic Motion:
Simple Pendulum and Mass-Spring
Systems
Torque
Rotational Motion
Conservation of Angular Momentum
Mechanical Waves and Sound
Electrostatics:
Electric Charge and Electric Force
DC Circuits: Resistors only
KINEMATICS DEFINITIONS
• Kinematics – branch of physics; study of motion
• Position (x) – where you are located
• Distance (d ) – how far you have traveled, regardless of direction
• Displacement (x) – where you are in relation to where you started
DISTANCE VS. DISPLACEMENT
• You drive the path, and your odometer goes up by 8 miles (your distance).
• Your displacement is the shorter directeddistance from start to stop (green arrow).
• What if you drove in a circle?
start
stop
SPEED, VELOCITY, & ACCELERATION
• Speed (s) – how fast you go
• Velocity (v) – how fast and which way; the rate at which position changes
• Average speed ( savg ) – distance/time
• Acceleration (a) – how fast you speed up, slow down, or change direction; the rate at which velocity changes
SPEED VS. VELOCITY
• Speed is a scalar (how fast something is moving regardless of its direction). Ex: v = 20 mph
• Velocity is a combination of speed and direction. Ex: v = 20 mph at 15 south of west
• The symbol for speed is s.
• The symbol for velocity is type written in bold: v or hand written with an arrow: v
AVERAGE SPEED VS. INSTANTANEOUS SPEED• During your 8 mi. trip, which took 15 min., your
speedometer displays your instantaneous speed, which varies throughout the trip.
• Your average speed is 32 mi/hr.
• Your average velocity is 32 mi/hr in a SE direction.
• At any point in time, your velocity vector points tangent to your path.
• The faster you go, the longer your velocity vector.
CHECK FOR UNDERSTANDING
What is the distance for each segment of motion
A to B, B to C, C to D?
What is the displacement for each segment of motion
A to B, B to C, C to D?
There are various ways
that we represent Motion:
Graphical
Equations
Motion
Maps
Graphical
Using a Cartesian Plane to show how the object
moves in reference to a certain time frame
Example:
Graphical
Using a Cartesian Plane to show how the object
moves in reference to a certain time frame
Examples:
A
B
What is the object
doing in each segment?
CHECK FOR UNDERSTANDING
x
t
A
B
C
a. Not Moving
b. Moving in the positive direction at a constant rate
c. Moving in the negative direction at a constant rate
d. Speeding up then slowing down
1 – D Motion
What is the object doing in section A?
x
t
A
B
C
a. Not Moving
b. Moving in the positive direction at a constant rate
c. Moving in the negative direction at a constant
rate
d. Speeding up then slowing down
1 – D Motion
What is the object doing in section B?
x
t
A
B
C
a. Not Moving
b. Moving in the positive direction at a constant rate
c. Moving in the negative direction at a constant
rate
d. Speeding up then slowing down
1 – D Motion
What is the object doing in section C?
x
t
A
B
C
A … Starts at home (origin) and goes forward slowly
B … Not moving (position remains constant as time
progresses)
C … Turns around and goes in the other direction
quickly, passing up home
1 – D MotionANSWERS
Motion Maps
Using a Pictorial representation to show how the
object moves in reference to a certain time frame
Examples:
Motion Maps
What is the difference between these motion maps?
Can we also make a graph of this motion?
Motion Maps
More Examples
CHECK FOR UNDERSTANDING
What is the object doing in each case?
Write down your description in words.
Can you make a graph of this motion?
Assume one second as the time
between each capture of motion
Equations
Using Variables to represent the motion of an
object for a specific time frame
Let’s do an experiment first…
Example:
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