Mr. Finau
Applied Science III
LINEAR MOTION
What does the phrase
“Everything’s relative” mean?
 Observations come from a perspective
 Every perspective can reveal a different
conclusion
What does the phrase “Motion is
relative” mean?
 Motion depends on your perspective
 An object can appear
to be moving from
one perspective, but
not from another
Distance & Displacement
What is Speed? What is Velocity?
What’s the difference?
 Speed is the rate at which an object moves
 “How fast an object moves”
 Velocity is the rate at which an object
changes position
 “How fast an object moves & what direction”
 Speed gives you an amount; Velocity gives
you an amount and direction
What are the units for
speed/velocity? Can you come
up with an equation for it?
 In metric, we use meters/seconds (m/s)
DISTANCE
VELOCITY 
TIME
 A rabbit runs 10 m in 2 seconds. How fast
does it run?

A
squirrel
runs
with
a
speed
of
4
m/s.
How
far

does it travel in 2 seconds?
What is the “ultimate speed
limit”…the fastest speed that
we know of?
 Speed of Light
 3 X 108 m/s
 Over 671 million miles per hour!!!
What is acceleration? Where do
you use acceleration in your
life?
 Acceleration is the rate at which velocity
changes
 Examples?
 Start running from stopped position
 Sliding into 2nd base in baseball
 Driving a car – push on accelerator, brake, or
turn the wheel
What’s the difference between
acceleration and velocity
 Velocity is the change in position over a period
of time
 Acceleration is the change in velocity over a
period of time
An apple falls from a tree;
does it accelerate? Why?
 Yes, a falling apple accelerates
 Its speed changes from zero to moving…
 Gravity causes acceleration
vertically
What is free fall? How much do
you feel like you weigh when
you’re in free fall?
 Free fall is when an object is
only acted upon by gravity
 You feel weightless
 Is there a difference between Weight & Mass?
 Yes, mass is the amount of matter, weight
depends on gravity
A ball is thrown vertically upward. What
happens to the ball’s velocity while
it’s moving upward?
 The ball slows down as it moves upward
What is its velocity when it reaches its
maximum height? What’s happening to the
direction the ball is moving at this
point?
 Velocity is zero; stops moving for a
brief moment
 The ball’s velocity is changing
direction
What happens after the ball changes
direction? What causes this?
 Starts moving downward
 Gravity pulls the ball downward
At what part(s) of the ball’s
flight is it accelerating?
 The ball accelerates during all parts of its flight
If an object has a positive
acceleration, what is happening to the
object velocity and distance traveled?
 Velocity increases (at a constant rate)
 Distance increases (exponentially)
 Exponentially – travels farther & farther each second
If an object has a negative
acceleration, what is happening to the
object velocity and distance traveled?
 2 possibilities:
 Velocity is decreasing
 Distance still increasing
 Velocity is increasing in negative direction
 Distance increases in negative direction
If a turtle slides across the beach with
a constant speed of .25 m/s, what is its
acceleration?
 Acceleration = O
 Key words – Constant Speed
If a car is traveling eastward, can its
acceleration be in the westward
direction? How?
 If a car is slowing, it has a negative
acceleration.
 If eastward is in the positive direction, what’s in
the negative?
 Westward, so Yes!
Graphing Motion
Situation
 Let’s discuss in terms of a car that is driving
with a constant acceleration of 1 m/s2
Keys to Graphing Motion
 Identify which variable
is the dependent
variable
 This is the variable on
the y-axis
 will change depending
on independent
variable on xaxis(usually time)
Keys to Graphing Motion
 Determine what the
dependent variable is
doing
 Whether it is:
 Zero
(no value; there is none)
 Staying Constant
(value doesn’t change)
 Increasing/Decreasing at a
constant rate
(typically just a diagonal)
 Increasing/Decreasing
exponentially
(typically a curve)
Keys to Graphing Motion
 Understand what is
happening to object
 Imagine what the object is
doing in relation to the
dependent variable
 Three Variables:
 Distance
 Velocity
 Acceleration
 For example – if velocity is
constant, you know
acceleration is zero, and
distance will increase at
constant rate
Keys to Graphing Motion
 Describe/Graph the
other variables vs time
 Be able to fully describe
what is happening to
the other variables of
the object
 If you’re given velocity,
be able to describe
what is happening to its
distance and
acceleration
Back of Worksheet
Given: _________________
Describe other variables
Review – Quiz tomorrow
 Review your notes carefully
 Any questions in particular?
 Remember Speed equation – 3 math questions
 Hint to remember  mph = miles/hours
 Review how to graph when discussing distance &
velocity – 2 graphing questions