Auto and Falling Object Interaction
Auto and Falling Object Interaction
(OP)
Does anyone know of a study relating auto speed/weight to being stopped by or rolling under a vertically falling object of various weights and velocities and geometries? In other words, when a car is hit by a vertically falling object, at what point does a car get stopped dead in its tracks with the object remaining in place crushing the car or roll under it and continue traveling with lesser damage? I can imagine a very heavy object and a fast-moving car coming to a halt. On the other hand, a slow-moving object and a fast-moving car, may have the car still partially crushed but moving out from under the object.
RE: Auto and Falling Object Interaction
Rod
RE: Auto and Falling Object Interaction
RE: Auto and Falling Object Interaction
Most practical application was allowing for winds, side slip and currents when navigating boats or aircraft.
I can't remember any formulas now, but as I recall you simply graphed the velocities with the two knowns as the X and Y axis. In this case use the momentum
(half the mass times the square of the velocity as I remember after 40 years)
Regards
pat
RE: Auto and Falling Object Interaction
Best of luck in your search. This subject is something that hits very close to home. I have lost loads a couple of times and had workmen injured as a result. Not good.
Rod
RE: Auto and Falling Object Interaction
1) The first part would be to determine the coefficient of friction of the combined objects. For this, a drag test with the crushed car and weight (on the same type roadway) would provide a reasonable first approximation of the friction coefficient.
2) The second part is the impact phase which would be a simple linear momentum problem in the vehicle travel direction.
This would at least provide you with an estimate of the minimum speed for the vehicle.
Kevin
RE: Auto and Falling Object Interaction
Actually i think there would be to many variables, was the vehicle able to support the weight for a fraction of a second and continue rolling, or did and axle break, did both axle's break? These would all have an effect on the friction applied to the road do to the amount of the vehicle that was contacting the road. I think you would have to recreate it to be sure. But it seems to me there should be other evidence at the scene such as skid marks or gouges on the road. I know you can figure out vehicle speed from skid marks, but i imagine trying to figure it from gouges from vehicle parts would be totally different.
-Jon