The discussion centers on the dynamics of a car emerging from a ditch, specifically addressing the mechanics of why the front wheels lift off the ground while the rear wheels remain in contact. Key factors include the inclined velocity vector at the hole exit and the shifting center of mass towards the rear. The participants explore the equations of motion, particularly the parabolic trajectory described by Z(t) = V_0t + (1/2)gt^2, and the implications of angular momentum on the car's rotation. The conversation highlights the need for a comprehensive model that incorporates vehicle suspension dynamics and the effects of wheel size on motion.
PREREQUISITESAutomotive engineers, physics students, and anyone interested in vehicle dynamics and the application of physics in real-world scenarios.
So you confirm that the 3rd element in the wheels coordinate expressions is neessary. I'll reflect a bit more on this.haruspex said:Ah, yes, I see my mistake. In post #92 I omitted an "h+" at the start of the formula. It's in my spreadsheet, but I missed it.
##V_0z## should be ##=ω_0 L##.alex33 said:Before starting the simulation of phase 2 (free fall), I ask you to confirm the starting data:
##V_0x = V = 2,52 m/s ## (Chord length / 18 frames ...I think it is the most reliable data)
##V_0z = \frac {1}{2}V* \tan(α)##
##ω_0 = \frac {1}{2L}V* \tan(α) - (\frac {3g*L}{h^2+4L^2}*4/24)##
##X_0c= \frac {chord-length}{2}-L##
##Z_0c = \frac {(ω_0 + \frac {1}{2L}V* \tan(α))}{2} * L * 4/24##
##θ_0 = \frac {V * \tan(α)}{2L}*4/24##
Thanks
The first model is the absorption of sharp edges of the tires, then the spring mass shock model. Otherwise this buggycar will drive anyone buggy without more assumptions being defined or become just a wooden car with no suspension and solid rubber tires with an extremely rough ride.alex33 said:Thanks Tony !
we went from theory to numbers just to verify the first proposed solution to the problem, with respect to a real event, but identifying the correct physical model is always the main objective of the question I asked in this thread. So thank you for your comments on which I and the other friends who have made themselves available will reflect for sure.
Dear Haruspex, do you check the values I send you? Please take a look at last calculations we shared. Thanksharuspex said:##V_0z## should be ##=ω_0 L##.
##Z_0c ## needs "h+", as discussed.
For ##θ_0## I use the average rotation rate during del t:
##(\frac {V * \tan(α)}{2L}+ω_0)/2*4/24##
I will do, but did not get a chance today.alex33 said:Dear Haruspex, do you check the values I send you? Please take a look at last calculations we shared. Thanks