1. SPEED
Investigation 2

2. Part 1 Who 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 object’s 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 object’s 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 13-15 Who 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 Travel Part 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 Distance t Speed 100 km 2 h 75 m 3 min. 60 km 4 h

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?
What’s 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
Speed t
Distance
75 km/h
2 h
8 m/s
10 s
5 cm/min.
60 min.
94 m/s
1.8 s

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: v=d/ t
Distance Equation: d=vx 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 object’s 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, there’s 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.

29. 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 doesn’t 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 car’s average speed as it travels 200 cm down your ramp?
You will be assigned an elevation.

31. What you’re 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 car’s 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 object’s 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 object’s 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 elevation vs. speed. Elevation on the x-axis and speed on the y-axis.
Label your table Mable!!!
Determine the number interval for both variables and number the axes.
Plot the points.
Elevation and speed start is (0,0).

37. Time Distance Graph 2nd graph, different kind of graph
You are going to start each car at (0, 0) so the graph will end up looking like a linear equation/xy graph
The x-axis will be labeled time, and the y-axis distance.
Every point will end at ?

38. 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?

39. 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

40. How Fast Do Things Go? Read pgs. 7-10 Complete the worksheet. Homework
Average Speed Practice WS 24 and 25
Next – Investigation 2 Assessment