Examination of an automotive crash test

[Bobthefreeradical]

Given { KE=.5M(v^2)} the act of ramming a car into an immovable barrier and the loss in speed from first contact and when the car totally stops, can be described as exponential in nature. Just like that of a Capacitor discharge curve.
is that plausible, or for that matter solid accurate?

 

[berkeman]

Please keep in mind that we do not allow real-world crash reconstruction threads here at PF. But to the extent that your question is general in nature, we should be able to help you with it.

Do you understand how crush zones work on cars? Have you done any searching to try to find an answer to your question? You could probably use a Google search like accelerometer plot of car crash tests to find typical deceleration curves...

 

[berkeman]

You could probably use a Google search like accelerometer plot of car crash tests to find typical deceleration curves...

I refined this a bit by using a Google Images search on accelerometer and velocity plots of car crash tests and got better hits. It looks like the velocity profile of a well-designed car will try to minimize the peak deceleration during the crash, which makes sense. So the profile of the velocity during the crash deceleration is a fairly straight decreasing line, which means that the deceleration forces felt by the passengers is fairly constant during the crash duration in order to minimize injuries. If the velocity profile were exponential, you would have higher peak deceleration forces at first, and then decreasing forces after that. Not very healthy...

From one of the search hits:

(BTW -- Note that the title of this graph is misleading; the vertical axis is the Velocity, not the Change in Velocity)

https://www.researchgate.net/figure...t-car-in-different-crash-tests_fig1_266397454

 

[Bobthefreeradical]

I see, its a function of "crumple zones" & I can guess that without crumple zones a vehicle would experience an exponential curve for its deceleration. Thanks for the info, Sorry about not going on a search for info before posting this.

I was thinking more like a non-crumple zone equipped vehicle, indeed much closer to those theoretical discussion in physics classes . . . oh well . .