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In support of all the students who are displaced from school due to the Corona virus. Access to physics zone and chemistry zone lessons are now available free of charge. This will be maintained at least through August 1st 2020. Learn and be well.

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Crash Tests without Seatbelts

Cars are designed with crumple zones so they may slow down over a longer period of time, which keeps the force smaller (see impulse).   However, this safety feature alone will usually not prevent serious injury or death to the occupants of a car during an accident.  The crumple zone only slows the car more gradually.  The only way it slows the occupants more gradually is if they are attached to the car.  Otherwise, the car may come to rest more slowly but the people come to rest immediately upon striking the already stopped interior of the car.   Stopping in a small amount of time means the force must be very large.  This video clip shows some very dramatic scenes of car crash tests with test dummies who are not wearing seat belts.  Specifically look for cars crumpling and people stopping in very small amounts of time. 

Crash footage from the National Transportation Safety Board