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University of Nebraska–Lincoln

Mid-America Transportation Center

Teacher Resource Center

Lesson Overview
Lesson Title:
How Bad Was It?

Teachers:
Mr. Peter Gomez (Primary)

Brief Description:
In this lesson the students will use a program called Logger Pro to analyze a video clip to determine the impulse force acting on the crash test dummy. The activity is followed by discussion of the amount of damage impulse forces can cause to the human body. There are a couple of video clips that address how engineers try to reduce these forces during a collision.

If you do not have logger pro you can download a trial version from http://www.vernier.com/ or other sources on the internet. (becareful because some of the trial versions will not allow you to insert a video clip)

Topics Introduced:
Impulse forces, safety design

Transportation, Distribution, and Logistics Curriculum Framework Components Addressed:
Facility and Mobile Equipment Maintenance
Transportation Systems/ Infrastructure Planning, Management and Regulation
Suggested Grade Levels:
10th Grade
11th Grade
12th Grade

Subjects:
Science
Standards Taught:
12.3.4 Science 2003

Lesson Information
Learning Expectations:

From this activity the students are expected to be able to analyze the video to determine the velocity of the car before and after the impact by analyzing a video clip. The students use this information to calculate the acceleration of an occupant, and the force needed to cause this type of acceleration. After watching the first video clip, the students are made more aware of some of the safety features that are designed into today's vehicles. The second video clip is meant to introduce the students to a career that applies the laws of motion every day.

There are post lab questions in the Powerpoint presentation that are meant to check for level of understanding the students take from this activity.

Plan Of Action:

PLAN OF ACTION

This lesson is designed to be an additional lesson in the forces unit covered during the first semester of my physics class. The students will already be acclimated to using the Logger Pro software to collect data using Vernier equipment. The students will previously been exposed to analyzing position vs. time graphs and velocity vs. time graphs to determine an acceleration rate. The students will have already discussed the concept of inertia before this activity.
The importance of the demo before doing the video analysis is to provide them a tangible example of inertia at work. It also sets up the idea that when we ride in a vehicle we also have inertia. Our inertia is changed by an impulse force. This force can be calculated as long as we know the mass in kilograms and the acceleration in m/s using Newton’s second law (F=M*A).
The video clip the students will analyze shows a front impact test of a 2006 Charger travelling at 25 miles per hour. After importing the picture into the Logger Pro program they will set the scale based on the wheel base of the charger being 120 inches or 3.07 meters. The students do this by using the yellow ruler tool button, then click-n-drag from the center of the front wheel to the center of the back wheel. After the scale is set the students will position the car to the point where if first enters the screen. They will then use the red location button, and plot the location of the center of the front wheel. If they do this correctly the program will automatically advanced to the next frame. I have them plot the position before and after the impact with the wall to discuss the change in velocity in greater detail later. After they get done plotting the points the program automatically makes a position vs. time graph and a velocity vs. time graph (complete step by step instructions on how to use this program are outlined in the handout "video_and_logger_pro" found at the end of this lab). I ask the students what the velocity of the car was before and after the impact. They use the slope of the line to determine this. Knowing the velocity before and after the impact will allow them to calculate the acceleration of the car and the crash test dummy inside it. Upload the file "video_and_Logger_Pro" at the end of my lesson for step by step instructions on how to use the software.

If you do not have access to Logger pro, look at the paper called "low-dow version of lab".

I have the students use a mass of 75 kilograms for the crash test dummy. Knowing this mass the students can calculate the impulse force acting on the crash test dummy. Once these values are obtained, the students are shown the data table in the PowerPoint presentation that depicts what type of injuries could result by different amounts of force. For more discussion have the students look at the video clip itself and count the number of video frames that go by during the impact. (From the time the car touches the wall, to the time it leaves the wall.) I tell the students that the video was shot at 60 frames per second. And they can use this to calculate the time elapsed during the impact. (I am guessing at this but somebody could verify it if they counted every frame, and consider that the entire video clip is eight seconds in length.) This time could be used to determine the how long the force is being applied.
This information could be used in the discussion of how engineers try to design ways to increase the duration of time during an impact to reduce the forces applied to the occupants of the vehicle.
In the last part of the PowerPoint presentation there is a video that discusses some of the safety devices that are built into a car, and how they can help safe lives. This video clip is followed by a brief introduction to the Midwest Roadside Highway Safety Center at the University of Nebraska.

Data Set Used:

Please look in the uploaded file for the data set used. This should include a short video clip titled "video.mp4". There is also an example data set saved in LOGGER PRO format to look at to see what type of data can be obtained from the video clip. The raw data set is titled "Charger analysis.cmbl"

Materials Needed:

Any toy that demonstrates the concept of inertia will do. Having more than one toy is helpful so the students them selves can try to figure out how it works.

The students need to have computer access.

The Software used was called Logger Pro. It can be purchased from several outlets, but is commonly used in conjunction with Venier probes and equipment. The version I currently use is 3.8.4. Some older versions have problems inserting videos clips unless they are in specific formats. They would only import AVI format.

The video clip was found by doing a video search using google.

The facts about the charger were also found on the internet by looking at information from the dealer's brochure on the car. The information I found important was the wheelbase data, because it was used to "set the scale" or give the program a known distance in the video for reference purposes.

The students were asked to print off the graphs that they had made and place them in their respective lab books along with the post lab question found on the second to last slide of the presentation.

If you cannot get access to logger pro as your video analysis software, please look in the additional resouces link for "low dow version of lab".

Preparation Period:

The preparation for this activity is minimal if your district has access to Logger Pro software. During class this year I choose to have the students work in groups of two. The major prep was walking around the room downloading the video from my flash drive to the students computer after they had logged on. In class it took me approxiamately 15 minutes to install the video clip on 10 labtop computers.

Any toy that demonstrates the concept of inertia can be used as a demonstration to help set up activity. If you choose to do this you might have to spend some time setting up for this.

Implementation Period:

This activity was implemented during a unit on unbalanced forces in my class. The entire activity including the discussions, video analysis, videos and post activity quiz was accomplished in a 90 minute block class.

We had previously discussed how to use the Logger Pro Software, how to determine the velocity of an object from a position versus time graph,the law of inertia and the law of acceleration.

This activity made a great transition into the topics of impulse forces and momentum.

Science, Math, Engineering and / or Technology Implications:

This activity introduces a method that engineers can use do determine the impact force experienced during different velocities for a car. It is followed by a video that discusses safety considerations a car manufacture include in vehicle design. There is also a short video that discusses safety designs that we might not be aware of during our daily commute.

Unexpected Results:

One of the biggest unexpected results that seems to arrise from this activity is student wanting to bring in their own video clips to analyze. They can find all kinds of videos on the internet of vehicle accidents, and they are interested in analyzing these videos.

The students are also very interested in the data on how much force is needed to cause the different types of injuries. They want to know where they can find this type of data, and I make sure to point out that the force of 10 Newton's is a pretty conservative value for an impact involving a car doing 25 mph, and we usually do some other calculations on how fast you would need to be going to experience the other forces.

From my perspective I found this activity as a great way to introduce the concepts of momentum and impulse forces. I plan of returning to the data later on during the energy unit and discussing this video from the perspective of energy transfer conservation.

Considerations for Diversity in Education:

This activity doesn't introduce contributions from a diverse group of scientist but does apply equally to all of the students that will be getting behind the wheel of a vehicle. Each and every student knows of somebody that has been in a traumatic accident. The types of possible injuries that can be incurred can be greatly reduced by using the safety equipment in the car properly, and reducing their speed.


Lesson Files
Video.mp4
video used imported into logger pro of a 2006 Charger during a frontal impact.
[size: 337468] [date uploaded: Dec 05, 2009, 11:29 pm ]

Charger analysis.cmbl
this is an example of the raw data that can be obtained in Logger Pro after analyzing the video.
[size: 25844] [date uploaded: Dec 05, 2009, 11:30 pm ]

How Bad Was It PowerPoint
This is the powerpoint I used during the initial presentation during the summer of 2009. Feel free to use/edit any part of it.
[size: 220672] [date uploaded: Dec 05, 2009, 11:33 pm ]

Low Dow Version of the Lab
this gives an alternative approach to doing the lab if you do not have access to the logger pro software, but you do have access to a computer and a multimedia projector.
[size: 27648] [date uploaded: Mar 08, 2010, 5:21 pm ]

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