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: