Physics ~ Motion
Frame of Reference
Objects are moving
 How they are moving depends on your
Frame of Reference
 Comparison to other objects
 Ex. Your body compared to the car
 Ex. A fly inside the car (cheeseburger
on dash)
 Ex. Your body compared to Earth
 (1800 km/h) sitting still – How can you
speed it up?

Choose your measuring stick
Height
 Walking distance
 Car’s movement
 Fly’s movement
 Earth’s movement
 Your movement inside the car when it is
stopped
 Make sure you use appropriate
measurement for the most accurate
measurement

Stand Up…
Take a piece of paper & pencil with you
 Find a square on the floor to stand
where nothing is in front of you for at
least 7 squares.
 Then follow the directions as they are
read aloud to you
 1. Put something in
your square to mark
where you started

2. Move 7 squares forward
 3. Write down how far you have traveled
 4. Move backward 4 squares
 5. Write down how far you have traveled
 6. Write down how far away you are
from your beginning square
 7. Move backward 3 more squares
 8. Write down how far you have traveled
 9. Write down how far away you are
from your beginning square
 You should be back at the beginning

Distance vs. Displacement

Distance – how far an object has
traveled

Displacement – how far an object is
from is beginning point
Need 10 yds to get the first down…
 What happens when the quarterback gets
sacked behind the line of scrimmage?
 What does the team do if they’re on 4th down
and 18 yds to the first down
line?

 PUNT
the ball
Displacement vs. Distance
What is your distance traveled from
home now?
 What is your displacement from home
now?
 Your distance traveled from home when
your return this evening?
 Your displacement from home when
your return this evening?

Figure it out…draw it out
If I left home this morning and drove 3
blocks north, turned east & drove 3
blocks, then turned south & drove 3
blocks…
 What is my distance?
 Displacement?
 You just drew vectors
 How could I have made the trip shorter?
 What would my distance be then?
 My displacement?

Speed
SI unit = m/s
 Speed = distance
time
 Average Speed = Total Distance

Total Time


v=d
t
Instantaneous speed
Speed in that instant
 Where do we find a meter for
instantaneous speed?
 Car

The Race for Rose Speedway

Make a table like this:
RACER DISTANCE METHOD TIME

HOW
FAST
Write Objective, Materials, Procedure,
Hypothesis
Copy these steps for lab
1. Get a meter stick, 2 pieces of
masking tape (or chalk), & stopwatch
 2. Measure a distance of 10 m (mark
both ends with a piece of masking tape
or chalk)
 3. Decide on 5 different ways you can
travel 10m
 4. Complete your race (make sure you
fill in your data table as you go)

Analysis questions to answer on your lab paper
1. Calculate how fast each “race” was
 2. Which “race” method was the
fastest?
 3. How do you know?
 4. What is the unit of measure for “how
fast?”
 5. Does it matter if the same person ran
each race?
 6. Make a line graph of your race
methods (use the x-axis as time)

Distance Time Graph
What you set up for your Race lab
 What do the lines on your graph
represent?


http://www.authorstream.com/Presentation/emphoto2003-290714-tortoise-hare-entertainment-ppt-powerpoint/
The Slope of your line represents speed
 What if you marked your location every
second and you had stopped at the 5m
mark for a few seconds…what would
the line look like?

It’s all relative…
Car is sitting still at a stoplight
 How fast is it moving?
 Relative to the road?
 0 km/hr
 Relative to the Earth?
 1800 km/hr
 If the car was moving and the
speedometer showed 80 km/hr….…
How fast is the car moving relative to
the Earth?

Velocity - It’s a vector
Vector = a straight line segment whose
length is magnitude and whose
orientation in space is direction
 Combine (add) vectors when more than
one velocity is involved (p.337)
 SI unit is m/s

Changing Velocity = Acceleration
Acceleration is the rate at which velocity
changes
 Acceleration is a vector too
 SI unit is m/s2
 Free fall on Earth = 9.8 m/s2
 When direction changes, there is
acceleration even if the speed doesn’t
change
 Remember:
Velocity = speed & direction

Acceleration

Acc = change in velocity
total time
a = (vf – vi )
t
Figure it out…
Car traveling at 10 m/s starts to
decelerate steadily. Comes to a
complete stop in 20 seconds.
 What is its acceleration?

- 0.5 m/s2
 Airplane travels down a runway for 4.0
sec. with an acceleration of 9.0 m/s2.
What is its change in velocity?
 36 m/s

Worksheet for you!
 Yes, this will be on your Exam!

Distance Time Graph
What you set up for your Take a Walk
lab
 What do the lines on your graph
represent?
 The Slope of your line represents speed
 What if you marked your location every
second and you had stopped at the 10m
mark for a few seconds…what would
the line look like?
