Post on 01-Jul-2015
Kinematics
Study of How Things Move
What am I doing?
How do you know?
Frame of ReferenceAll motion is relative. What does that mean?
Car Commercial
Describing Motion
What can we measure?Science is about Quantitative Descriptions
What relationship are we trying to determine?
From the useful measurements, what is our objective?
To find a relationship between what and what?
What should we do with the data?
So we are making measurements, but what do we do
with them?
• Table? What do we put in the table? So we need
signs for those things, right?o t=time and x=position (y if vertical)
• When our table is full of data, then what?o Graph it! We need axes. Which variable goes on which axis?
o Time is independent (x-axis)
o Position depends on the time (y-axis)
• Alright! Let’s do this! Wait, what are we doing?
The Breadcrumb MethodHow we collect data
Do NOT write down this data. It’s not yours!
• Mark Origin
• Mark Starting Point (different from origin, positive or
negative)
• Sync the stopwatch and the starting of the buggy
(figure it out)
• Use tape tick marks to mark the position of the back
of the buggy every 2 seconds.
Jobs• Meter Stick – grab a meter stick for the group
• Stopwatch – grab a stopwatch for the group
• Taper – grab a role of tape for the group
• Data Collector – take data in a table for the group
WhiteboardsWith your group, sketch your graph on a whiteboard.
Don’t use a meter stick or make tick marks, make a
general sketch.
Write the equation of line of best fit near your sketch.
When you’re finished, gather around for a … wait for
it… board meeting!
Get it?
Board MeetingClass discussion. Sit so everyone can see the boards.
I’ll help lead the discussion this time, but eventually
you won’t need me as much.
What’s the same about everyone’s boards?
What’s different?
The Take HomeSlope of the position-vs-time graph is Velocity.
Positive or Negative tells us direction.
Steepness tells us magnitude.
Constant Velocity Particle Model
Look at all the pieces of our model:
• Verbal piece from our observations
• “Breadcrumb” motion map on the floor/table
• Table of data points
• Position-vs-time graph features
What’s left in the CVPM?
• Velocity-vs-time graphs
The Test!
Homework“Motion Maps” Reading
It’s 1 page, front and back. There’s a lot of pictures.
Deal with it!
Put ?’s next to words you don’t know. Make notes in
the margin. Come ready to talk about motion maps!
Day 2 – Constant VelocitySched:
• Starter
• Recap
• Wkst 1
Starter: If you’re driving on the highway at 70mp…
A. How far down the road will you be in 3.5 hours?
B. How long will it take you to go on a 300 mile trip?
And the answers are…• Starter: If you’re driving on
the highway at 70mp…
• A. How far down the road
will you be in 3.5 hours?
o 245 miles
• B. How long will it take you
to go on a 300 mile trip?
oAbout 4.3 hours
Objective:
TLWBT read graphs,
table, motion maps
and written
descriptions and
express motion in
graphs, table, motion
maps and written
descriptions
Let’s RecapFrame of Reference
• In order to describe motion, you have to pick a “frame of reference”
o Frame of reference is always decided by the
observer
o In physics we often use a coordinate axis to
denote our frame of reference.
Frame of Reference
-x
-Y
x
Y
This is a familiar coordinate axis, but in physics it has a slightly different meaning.
Frame of Reference
• In this frame of reference, up is positive,
right is positive
• Down in negative, as is left
• Hence in physics a negative has no
value, it merely denotes direction
• This is necessary because direction has a
special distinction in physics; it separates
vector quantities from scalar quantities
Vector vs. Scalar
• A Scalar Quantity is one that has only magnitude – distance is a scalar
o Example: If you travel 500 miles that is a distance
• A Vector Quantity is one that has magnitude and direction – displacement is a vector
o Example: If you travel 500 miles North this is displacement
Distance and Displacement
• Distance is a scalar. Think about a pedometer or an odometer.
o Example: If you travel 500 miles that is a distance
• Displacement is a vector. Displacement is the shortest path from start to finish. “As the crow flies.”
o Example: If you travel 500 miles North this is displacement
Distance and Displacement
Let’s say you walk 5m to the right, 3 meters up, another 5 meters to the right, and finally 4 meters up.
Your distance is the total meters you walked: 17m.
Your displacement is simply the difference between finish and start: ~12m.
5m
5m
3m
4m~12m
Speed and Velocity
If you divide distance by time you get average
speed (scalar)
• Example: S = D/t = 500 miles/2 hours =250 mph
If you divide displacement by time you get
average velocity (vector)
• Example: Vavg = Δx/Δt = 500 miles North/2 hours
= 250 mph North
Motion Maps
Cooperative Learning
Whiteboard Worksheet 1I will present a problem from the worksheet.
In groups, you will talk through and solve the problem
on the whiteboard. Really work through it and make
sure each group member really understands.
We will talk about answers and misconceptions. Then,
as a class we can write correct answers and ideas on
our worksheets.
Day 3 – Constant Velocity
Sched:
• Starter
• Check Wkst1
• V vs T graphs
• Wkst2
TLWBAT interpret and draw V vs. T
Graphs.
Starter: How far does your
car travel when you one-
handedly text “LOL” to your
friends.
Velocity vs. Time Graphs
Let’s make some guesses!
Whiteboard Worksheet2
In groups, you will talk through and solve the problem
on the whiteboard. Really work through it and make
sure each group member really understands.
We will talk about answers and misconceptions. Then,
as a class we can write correct answers and ideas on
our worksheets.
Units of Area on V vs. T Graphs
Day 4 – Constant Velocity
Sched:
• Starter
• Motion
Detector Lab
• Quiz?
TLWBAT reenact physically any motion given in a prompt.
Starter: Find the total distance
covered and total displacement.
Buggy Lab Part 2Battle Royale
2m
Where will they hit each other?