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Projectile Motion - TVJA

By Lawrence Brown,2014-03-17 22:43
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Projectile Motion - TVJAProjec

Name(s): _____________________

_____________________

_____________________

_____________________

You may have played with Hot Wheels or Matchbox cars when you were younger. Part of the fun may have been racing your cars against your friend’s cars. Did you or your friend have a favorite car that was faster than the rest and almost never lost? In this lab we will explore reasons why your favorite car may have been so fast.

Photogate #1 Photogate #2 Book

Figure 1

Objectives

; Measure the speed of Hot Wheels cars using Photogates.

; Determine whose car is fastest and give possible explanation why it is the fastest.

; Explore the relationship between speed and mass of Hot Wheels cars.

Materials

; TI Graphing Calculator ; 2 Ring Stands

; LabPro Interface ; Buret Clamp

; DataGate Program ; 2 Thermometer Clamps

; 2 Vernier Photogates ; Triple Beam Balance

; Hot Wheels Track Set ; Meter Stick

; 4 Hot Wheels Cars ; Textbook

; Metal Physics Pole or extra ring stand ; Penny & Tape

Vocabulary

1. During this lab you will need to be familiar with some vocabulary. Using your

textbook please look up and enter the definitions to the following words.

Acceleration: ________________________________________________________

__________________________________________________________________.

Force: _____________________________________________________________

__________________________________________________________________.

Mass: _____________________________________________________________

__________________________________________________________________.

Speed: ____________________________________________________________

__________________________________________________________________.

Velocity: ___________________________________________________________

__________________________________________________________________.

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Hot Wheels Lab

Weight: ___________________________________________________________ __________________________________________________________________.

Procedure

1. Working in groups of four, record the name, color, and weight of each of your

four Hot Wheels cars in the data tables found on page 7.

2. Hypothesize with your group which car you think will be the fastest and why.

(independent variable) Hypothesis: If _______________________________________________________ __________________________________________________________________

(dependent variable) ________________, then _____________________________________________ __________________________________________________________________.

3. Set up track as demonstrated by your teacher and as shown in Figure 1.

a. Connect all segments (5 long and 2 short pieces) of track using the six

track connectors.

b. Place a metal physics pole into the socket at the far

end of the lab bench. Attach a buret clamp to the

pole. Attach the Hot Wheels track clamp to the

buret clamp.

c. Attach the track to the track clamp. Raise or lower

the buret clamp until the track surface is elevated

30cm above the table top.

d. Place your textbook at the end of the track to block the cars from falling

onto the floor during the time trials.

4. Position the Photogates over the track so the cars roll through the two gates.

a. Attach one photogate to each of the two ring stands

using a thermometer clamp for each.

b. Raise each photogate so that it is about 1cm above

the table top. This height can be achieved easily by

sliding the meter stick under the photogate since it is

clamp. When an object passes through a

Photogate, it blocks the passage of light from one

side to the other. If the photogate is resting on the

tabletop it will

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Hot Wheels Lab

be too low and the walls of the Hot Wheel track will block the sensor. If

the photogate is too high it may miss detecting your car altogether.

c. Position the Photogates so that they are exactly one meter apart from

each other.

5. Photogate #1 is the gate closest to the top of the Hot Wheel track. Photogate

#2 is the gate at the bottom of the track closest to the end. Connect Photogate

#1 to the DIG/SONIC 1 port of the LabPro interface. Connect Photogate #2 to

the DIG/SONIC 2 port of the LabPro interface.

6. Make sure that the car does not strike the side of either of the Photogates.

Adjust the Photogates if necessary making sure that they are still one meter

apart from each other.

7. Turn on the calculator and press the button. Scroll down until you

see the VST Apps program. Select VST Apps and press .

8. Press 2 on the calculator number pad to start the DATAGATE program.

Press to reset the program.

9. Set up DATAGATE for the pulse mode.

a. Press 1 to enter setup from the main screen.

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Hot Wheels Lab

b. Press 4 to select Pulse mode from the PHOTOGATE SETUP screen.

Pulse mode is used to measure the time between successive blocks of

the two gates.

c. Press 2 to select Two Photogates from the HOW MANY PHOTOGATES?

screen.

d. DATAGATE will prompt you to enter the distance between gates in

meters. In two gate mode the distance between gates can be entered to

calculate a velocity based on time interval. Enter the distance between

gates as 1 meter and press .

e. Press 1 for OK from the SETTINGS screen to return to the main screen.

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Hot Wheels Lab

10. Observe the reading on the calculator screen. Block a Photogate with your hand;

note that the Photogate is shown as blocked (--X--) on the calculator screen.

Remove your hand and the display should change to unblocked (--0--).

11. The calculator will measure the length of time between when the first photogate

was blocked and when the second photogate was blocked. You can see how this

works by sending a Hot Wheel car down the track. Prepare the calculator to do

this.

a. Press 2 to select START from the main screen.

b. Send a car down the track. Note that the Trial Number and Time(s) are

recorded. Since this was the first time you sent a car down the track it is

recorded as Trial Number 1 followed by the time interval in seconds (s)

that it took the car to go through both gates. Send another car down the

track and note that the calculator records the event as Trial Number 2

followed by a new time.

c. Press to end data collection.

12. Lab Team Job Rotation. Have one person release a car at the top of the track

while one person at the bottom of the track uses the calculator, one person

catches the car, and the fourth person records times on the data table. Rotate

jobs after each person has completed the time trials for his or her car.

13. Please remember that when you “release” the car, you are letting go of the car,

not pushing” it down the track. Press 2 to START data collection. Send your

first car down the track four times. Record each time interval in the Data Table

for the first car. After the last trial, press to end data collection and return

to the main screen.

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Hot Wheels Lab

14. Press 3 to select GRAPH from the main screen.

15. Select PULSETIME and press . The Pulse Time graph gives you data

points for each of your four time trials. You can move the blinking “x” cursor

over the data point for each time trial by pressing the forward button or the

backward button . Note that the trial number appears on the x-axis and the

time value appears on the y-axis. Compare these numbers with the times you

entered into your data table. What did you discover?

To exit the Pulse Time graph press .

16. Select VELOCITY and press . The Velocity graph gives you data points for

each of your four time trials. You can move the blinking “x” cursor over the data

point for each time trial just like you did on the Pulse Time graph. Compare

these Velocity numbers with the times you entered into your data table. What

did you discover?

Enter the Velocity for each time trial into your data table.

After you have recorded your velocity data into your data table press to

exit the Velocity graph.

17. Inspect your data. Did you get the same value every time?

Determine the average, maximum, and minimum times and velocities, and enter

them in your Data Table. To calculate the average for each car add the four

time trial values together and divide by four. What one value would be most

representative of all four measurements?

18. Press 1 to return to the main screen. Repeat steps 12 17 for the remaining

three Hot Wheels cars.

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Hot Wheels Lab

Data Tables

Car #1 ï¼› Follow steps 12 17 for Car #1

Car #1(name) Trial Time Velocity (s) (m/s) Color

1 Weight grams

2 Maximum Time (s)

3 Minimum Time (s)

4 Maximum velocity m/s Average Minimum velocity m/s

Car #2 ï¼› Follow steps 12 17 for Car #2

Car #2(name) Trial Time Velocity (s) (m/s) Color

1 Weight grams

2 Maximum Time (s)

3 Minimum Time (s)

4 Maximum velocity m/s Average Minimum velocity m/s

Car #3 ï¼› Follow steps 12 17 for Car #3

Car #3(name) Trial Time Velocity (s) (m/s) Color

1 Weight grams

2 Maximum Time (s)

3 Minimum Time (s)

4 Maximum velocity m/s Average Minimum velocity m/s

Car #4 ï¼› Follow steps 12 17 for Car #4

Car #4(name) Trial Time Velocity (s) (m/s) Color

1 Weight grams

2 Maximum Time (s)

3 Minimum Time (s)

4 Maximum velocity m/s Average Minimum velocity m/s

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Hot Wheels Lab

Notes

Speed and velocity are rates. They tell us how much distance is covered in a unit of time. Velocity can be expressed by the formula

v = d/t

where v = velocity or speed (in m/s), d = distance traveled (in meters), and t = time (in

sec). In this experiment, we study the velocity of a Hot Wheel car after it is released from the top of the track. The two photogates are used to measure the car’s velocity.

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Hot Wheels Lab

Analysis

1. Using the grid below make a bar graph to show the average times paired with the

average velocities of all 4 cars. Label the parts of your graph.

2. Discus your conclusions. Was your hypothesis correct? Why or why not?

3. Newton’s first law of motion states that an object at rest will remain at rest. And an

object that is moving at constant speed will continue moving at constant speed

unless acted upon by an unbalanced force. When you released your Hot Wheel

car at the top of the track what unbalanced force caused your car to go down the

track?

4. Newton’s second law of motion is best stated in the form of the equation:

Force = Mass X Acceleration

What role do you think mass or weight played in the outcome of your time trials?

5. Change the weight of your Hot Wheel car by taping a penny to it. Does the penny