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Momentum Alley Teacher

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Slowing Down the Effects of Momentum

When a vehicle is traveling at any speed, momentum is at work. When that vehicle has a collision or brakes quickly, the sudden change in momentum of the car, its passengers, and any cargo can cause injuries and damage because of the force. That is why car manufacturers have developed several safety features, such as seat belts, airbags, padded dashboards, and crumple zones to protect any riders who may be involved in an accident.

Seat belts and airbags are important devices as they are designed to slow the body down more gradually. Slowing down more gradually reduces the forces on the body during a collision. Seat belts and airbags are legally required to be installed in vehicles and there are many states that enforce seat belt laws to ensure riders are protected.

Padded dashboards are safety features that give riders a way to protect themselves in case an airbag does not deploy. Hitting the padding instead of the dashboard reduces the forces acting on the body during impact. This feature has a huge effect on the severity of head injuries from car collisions.

Crumple Zones were first developed in 1952 by Béla Barényi, who worked for Daimler-Benz. He designed a car with designated areas that could collapse and absorb the kinetic energy released in an impact. These zones are still designed and utilized by auto engineers. Vehicles are designed to collapse in a controlled way during a collision, absorbing and redirecting the force of the impact. Crumple zones are usually located in the front and back of the vehicles.

Teacher Tips icon Teacher Tips

Help students to recognize that all of the devices mentioned in this reading are not reducing the momentum of the car or directly reducing the impact forces that occur during collisions. Instead, these devices manage the impact forces so that their consequences are minimized. For example, an airbag in a vehicle is like placing an inflated balloon between the robot and the ball in the Exploring Velocity activity. The balloon could have diverted some of the impact forces away from the ball and therefore reduced the distance it traveled. That is similar to how an airbag prevents passengers' heads from damaging impacts with the interior of a car during a collision.

Motivate Discussion icon Motivate Discussion

Q: Cars used to be made out of steel and had little padding. What do you think led to adding safety feature requirements in cars?
A: Students should mention neck injuries (whiplash) and head injuries (concussions, brain damage), and a high number of incidents regarding deadly car crashes.

Q: How do vehicle safety features protect you?
A: Students should point out how airbags and seat belts can protect them from being thrown into the dashboard or through the windshield. The crumple zone lessens the impact of the collision on the human body.

Q: What type of safety features have been developed by engineers to protect younger children, and why?
A: The design of special car seats allows for the correct positioning of the seat belt to better protect the child.

Extend Your Learning icon Extend Your Learning

To expand this activity, ask your students to further research safety features, such as those mentioned above, in other types of vehicles (various types of airplanes, space shuttles, helicopters, and the like). They can also examine crash testing methods used by engineers to explore the limits of safety features.