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SCIENCE 911: Car Crash Testing

Crash test dummies are not as dumb as they look. In fact, they help save thousands of lives by playing victim in crash tests. In this segment, engineers and dummies collaborate in a series of tests designed to simulate what really happens in a two-car collision. Information from the accident reconstructions may be used to redesign cars and ultimately reduce debilitating injuries.

Activity 1: On a Collision Course
Activity 2: A Crash Test for Plastic

 BIOLOGY anatomy COMPUTER SCIENCE crash simulations MATH probability, statistics PHYSICAL SCIENCE acceleration, force TECHNOLOGY materials

ACTIVITY 1: ON A COLLISION COURSE

Enter the realm of unanswered questions and challenging calculations known as the forensic twilight zone!

• Your assignment: figure out who was on the ramp when the accident occurred and who was responsible.

• Your tools: a metric ruler and a protractor.

Begin by figuring out the crucial point that is halfway between routes 5 and 88 (Hint: see Officer D on the Data Chart).

To plot where each person's vehicle was at the time of the accident, make a number line to represent distance in kilometers from the midpoint of the ramp and the direction the vehicle is traveling in. Assume all vehicles travel at a constant velocity of 40 kilometers per hour and are on a direct course between Routes 5 and 88. Use the data chart and the clues to figure out where each suspect belongs on the number line. Label the time above each point and write the suspect's name below each point. (This is a logic puzzle; the distances are relative.)

DATA CHART

 Time: hr/min/sec Distance From Midramp* Suspect & Direction of Travel* Clue Vehicle, Tire Widths 9.01.00 2.0 West Dr. A + removes sunglasses, faxes x-rays sports car, 4mm 9.01.30 1.4 West Mrs. B - recycles for homeless seniors motorcycle, 3mm 9.02.00 0.6 East Miss C + sells lambskin powderpuffs jeep, 6mm 9.02.30 0.0 Officer D horse patrol, beeps for help mammal, curved 9.03.00 0.6 West Ms. E - lens filter cracks, videotaping ends moped, 2mm 9.03.30 1.7 East Trooper F + screeches to halt, jolts neck sedan, 5mm 9.04.00 2.0 East Mr. G - hands sweat, secures fleece seat mountain bike, 1mm

* Use time and distance information to place suspect on the ramp. "East" or "West" tells what side of mid-ramp suspect is on at the time indicated. "+" and "-" indicates direction suspect travels in.

NOTE: A number line is optional, but it may help figure out whose paths cross. Tire treads are important.

QUESTIONS

1. Does the data indicate an accident occurred?
2. Are the travelers piled up?
3. Do any tread marks meet?
4. If so, how many?
5. At what angle?
6. Who collides?
7. Is anyone immobilized?
8. If so, who?
9. Was everyone headed in the right direction?
10. If no, who?
11. 40 kilometers per hour = ? miles per hour (km x .621 = miles)

1. yes
2. no
3. yes
4. 3
5. 32 degrees
6. Dr. A and Mr. G
7. yes
8. Dr. A
9. no
10. Dr. A; her glasses fell off and she swerved into oncoming traffic
11. 25 mph.

LAB NOTES

The "On a Collision Course" activity uses math, logic and problem-solving skills.
• You may wish to broaden the scope of the activity with these questions: What happens if the exact point of intersection of two vehicles' paths occurs at the junction of an interstate highway and a local route? Whose responsibility is it to handle the accident, the local police or the state troopers?

• If students need help making a number line, show them how to use the data table to find the information they need. Put an arrow on the line to indicate direction suspect is traveling in.

• Note: tire treads are an important clue.

ACTIVITY 2: A CRASH TEST FOR PLASTIC

In this mini-test, you will test various plastics for durability. How well do they hold up in a crash test?
• To perform the crash test, you'll need soda cans, toy cars and samples of plastics. Fill four cans of equal size with rocks or pennies. To make the collision wall, cut pieces of plastic from various sources -- deli containers and packaging materials, for example. If you look on the bottom of the container, each is embossed with a resin code for recycling. Use these numbers to distinguish your samples. (1=polyethylene terephthalate, 2=high-density polyethylene, 3=polyvinyl chloride, 4=low-density polyethylene, 5=polypropylene, 6=polystyrene) Attach a can at the end of each plastic sample. (You can use a glue gun to secure samples onto cans.)

• Aim the car at the wall, power it each time by a finger flick and send it flying into the wall. Rate each plastic sample on a scale of one to six. Use your judgment to rate materials for durability, with the toughest at 6, and the weakest at 1. Perform six trials with each material. Take an average or mean value. Test those materials with the same rating again -- each six times. Again, calculate an average or mean value. Compare your ratings with other crash teams.

• Extensions: Use CO2 cartridges on technology cars. Design dual, triple, quadruple cartridge cars. Test again. How many cartridges does it take to collapse the toughest material?

CREDIT: Mary-Lou Clare, secondary instructor of math and science at South Orangetown Central School District in Blauvelt, New York, contributed the activities for this segment.

NOTES & DISCUSSION
• Crash testing has changed a lot since the 1950s when a typical test meant lifting a car with a crane and dropping it on its front end. In some early tests, engineers actually drove cars into barriers. After watching the Frontiers story, ask students to explain differences between the commonly accepted crash tests and the types of tests the Insurance Institute of Highway Safety recommends.

• What are some of the variables that determine the outcome of an automobile accident? Consider: road conditions, speed, weather, driver attitude and awareness, material and design of the car. What are some of the physics concepts involved in a two-car collision?

• Ask students to contribute information they have learned from their own experiences in driving or being a passenger. If you have students taking driver education, invite them to talk about what they've learned to prevent auto accidents.

• Invite a representative from the insurance industry or emergency medical field to talk to your class about preventing car accidents. In his or her experience, what is the most common mistake made by drivers?

• What cars have the best safety ratings? Why? This information can be obtained from the Insurance Institute for Highway Safety Communications Dept., 1005 N. Glebe Rd., Arlington, VA 22201.

•  Scientific American Frontiers Fall 1990 to Spring 2000 Sponsored by GTE Corporation, now a part of Verizon Communications Inc.