SPEED

1
SPEED

• Investigation 2

2
Part 1Who Got There First?

• Road Races
• In Race 1 the pogo stick and car started here.
  At the end of the race they were here.
• We were able to get the initial and final
  positions for both vehicles.
• We used position data and the distance equation
  to calculate which vehicle went farther.

3
First Arrivals

• So, which vehicle arrived first in each of these
  races?
• On Handout 5 it shows illustrations of two road
  races similar to the ones we studied previously.
  In the first race the white truck started here
  and the white car started here. At the end of
  the race their positions were here and here.

4
First Arrivals cont..

• Which vehicle got to its final position first?
• Which vehicle got to the 13-kilometer mark first?
• What additional information would we need to know
  in order to determine which vehicle arrived at 13
  km or its final postion first?

5
What is Speed

• In your journal write down the word speed and
  what you think that word means.
• Speed is the distance an object travels in a unit
  of time. The symbol for speed is lowercase v.
• We use the words fast and slow to describe an
  objects speed. If an object moves a long
  distance in a unit of time, we say it is going
  fast. If it moves a short distance in a unit of
  time , we say it is going slow.

6
Speed Cont.

• The units of speed are distance per unit time,
  such as kilometers per hour or meters per second.
  
• Why not miles?
• What units are used in track?
• A fast car might travel at 150 km/h. A leisurely
  walker might travel at 1 m/s.

7
More Speed

• An objects speed is related to time. A time
  interval is how long it takes for something to
  happen. The amount of time it takes for an
  object to go a certain distance determines its
  speed.

8
Worksheets 13-15Who Got There First?

• Three races
• Analog clocks
• Complete the three worksheets
• In your journal write down observations you
  learned or picked up on about speed.
• Like

9
Worksheet Observations

• When two vehicles start together and go the same
  distance in the same amount of time, they arrive
  at the final position together.
• If vehicles go different distances in the same
  amount of time, the one that goes farther is
  going faster.
• If vehicles travel for different amounts of time,
  you need to find out how far they both go in one
  hour before you can compare them.

10
The Infinite Line

• Open your books to page 1.
• Answer the following questions on a piece of
  notebook paper.
• What is time?
• What is universal time?
• What is a time interval?
• What are different units of time?
• What is start time?
• List three ancient ways of keeping time.
• Who invented a device that measured a second?
• Starting with seconds, list the measurements of
  time.

11
Time TravelPart II

• We just figured out how to figure out who got
  there first.
• Why do we need to know either how long it took
  for a vehicle to travel a distance , or how fast
  the vehicle was going? Write your answer in your
  journal.
• Complete WS 16. WS 16 ONLY!

12
Worksheet Review

• Be sure to write the speed as a rate
• ALWAYS!!!

13
Speed Algorithm
14
Do You Got It?

• Can you write the formula or algorithm for
  finding speed?
• What is the symbol for speed?
• What is the symbol for distance?
• What is the symbol for change over time?
• Whats the equation?
• V d/ t

15
Time Travel B

• Last question review
• Complete WS 17 with your table
• The initial and final positions of both vehicles
  are shown on one roadway.
• The vehicles travel at constant speed all the
  time no stopping or going faster and slower.
  The truck is now going half as fast as it was in
  the first problem.
• When you get to question 2d, work with the other
  in your group to figure out the equation for
  calculating distance.

16
The Distance Algorithm
17
Do You Got It?

• What is the equation for finding distance?
• d v x t

18
Definition Time

• Speed (v) how fast something travels the
  distance traveled in a unit of time.
• Speed Equation vd/ t
• Distance Equation dvx t

19
Assignments

• Read First in Flight and answer the questions on
  pg. 6. Answer the questions in complete
  sentences in your journal.
• Complete WS 18 and 19.

20
Part 3 Measuring Time and Distance

• What two pieces of information do you need to
  know about an object in motion in order to
  determine its speed?
• What is the definition of speed?
• What is the symbol for speed?
• What units are used to describe speed?
• What is the equation for calculating speed?
• If you know an object is traveling at a speed of
  45 kilometers per hour, how can you determine how
  far it will go in 10 hours?

21
Determining Speed

• Suppose you wanted to figure out how fast a
  bicycle was going. How would you go about it?
  Write the question and your answer in your
  journal.
• Four things you need to do
• Establish a starting position
• Establish an ending position
• Time how long it takes for the bike to travel the
  distance
• Use the speed equation to calculate the average
  speed for the bike.

22
Focus on Time

• In order to determine an objects speed, we need
  to measure the distance the object moved, and we
  need to measure how long it took to move the
  distance. We know how to measure distance we
  use a meter tape.
• How can measure the time it takes for the object
  to move the distance?

23
Stop Watches

• We have stopwatches for timing motion events.
  They are not toys and must be treated with care.
• The watches have cords attached. The cord is for
  hanging around you neck, not for swinging it in a
  circle. You will lose your opportunity to use
  the stopwatch if it is not hung on your neck.

24
Stop Watches cont

• The stopwatches have buttons. Do not press any
  of the buttons until we know what each button
  does.
• The button on the right turns the watch on and
  resets the watch to zero after an event has been
  timed. The watch turns off automatically after a
  minute of inactivity.

25
And more

• The middle button starts and stops the timing
  function. Press once to start timing press a
  second time to stop.
• Hold the watch loosely in your hand with your
  thumb over the start/stop button. Press it once
  and the stopwatch will start. Press the same
  button a second time to stop the watch.

26
Yes, theres more

• Read the elapsed time on the screen. The numbers
  represent hours, minutes, seconds, and hundredths
  of a second.
• Press the reset button on the right to reset the
  watch to zero. It is now ready to time another
  event.
• Practice time
• Stop at 1 s
• Close your eyes and stop at 5 s
• Time my hand
• Playing catch

27
Quizzy-Poo

• Complete the Response Sheet - Speed

28
The Dotcar

• We are going to determine the speed of dotcars
  rolling down slopes.
• These are electronic and we only get one chance.
  Each time you use these cars you will take utmost
  care and have a soft catch place.
• Each group is going to set up a ramp using a
  board and a black thing.
• The black thing should cover the bottom edge of
  the slope as a transitional piece.

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Dotcars

• On the floor for our first time.
• Your team will be assigned an elevation. Use
  science books and others to meet your elevation
  requirement.
• Lightly tape the black thingy on the board so it
  doesnt move.
• Place coats, pillows, etc. (not the big ones)
  near the end of the ramp. This will be called
  soft walls.

30
The Dotcar Experiment

• Two experimental questions
• How long does it take your car to travel 200
  centimeters down your ramp?
• What is your cars average speed as it travels
  200 cm down your ramp?
• You will be assigned an elevation.

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What youre going to do

• Measure 200 cm from you xi to your xf. Mark xf
  with a bit of tape.
• Put up your soft wall near the end of the ramp.
• Time several runs from the moment the car begins
  to roll until it hits the soft wall.
• Calculate the average time for a run.
• Calculate the cars average speed as it travels
  200 cm.
• Complete Part 1 only of WS 23.

32
Discussion

• Discussion Questions
• Did your car travel at the same speed during the
  whole run?
• How fast was it going at the beginning?
• How fast was it going in the middle of the run?
  At the end of the run just before it hit the soft
  wall?

33
Average Speed

• It is difficult to know how fast an object is
  going at any specific time. Like our Dotcars,
  many moving objects change speed all the time.
  Their speed is not constant.
• To get around this problem, we often use an
  objects average speed to determine how fast it
  is going. If we know how far something went, and
  how long it took, we can calculate the objects
  average speed.

34
Average Speed Cont.

• Average speed is total distance divided by the
  total time needed to travel the distance.
• What would be the speed of a Dotcar that went 200
  cm in 2.6s?
• What is the equation then for finding the average
  speed?
• Write the definition and equation on your Terms
  and Def. Page, and your equation page.

35
Sharing Data

• Part 2 of WS 23
• Complete the group data table as each table
  reports their findings.

36
Graphing

• Graph distance vs. time. Time on the x-axis and
  distance on the y-axis.
• Label your table Mable!!!
• Determine the number interval for both variables
  and number the axes.
• Plot the points. Write the elevation by each
  data point.
• Distance and time start is (0,0).

37
Analyzing the Data

• On the back of your WS answer the following
  questions.
• Which Dotcar traveled the fastest?
• Which Dotcar traveled the slowest?
• What is the relationship between elevation and
  speed?
• Which Dotcar graph line has the steepest slope?
• Which Dotcar graph line has the flattest slope?
• On a speed graph (distance vs. time) what does
  the slope of a graph line tell you about the
  speed of the object?

38
Using the Graph to Find Speed

• Take a look at Transparency 11
• These are data collected by some other students
  when they did this investigation. As you can
  see, students recorded the elevation, time, and
  distance, and they calculated the speeds as well.
• The average speed of the Dotcar on the 5-cm ramp
  is 48cm/s.
• If we put our finger on the 1s line and move up
  to its intersection with the graph line for the
  5cm ramp.
• From that point I can run a straight line over to
  the y-axis. The place where the straight line
  intersects the y-axis is the distance the car
  traveled in 1 s. The car traveled 48 cm in 1 s.
  That gives me the speed 48cm/s.
• Find the speed of the other four cars in the same
  way
• Find the place where the 1-s line intersects the
  graph line and run a straight line over to the
  y-axis

39
How Fast Do Things Go?

• Read pgs. 7-10
• Complete the worksheet.
• Homework
• Average Speed Practice WS 24 and 25
• Next Investigation 2 Assessment