Derby Talk

Instead of push pins, place two parallel elastic boundaries on the table, separated by less than the length of the bar. With the bar at a slight diagonal, push it toward the far boundary (with no rotation). Here is what I think happens: The outcome you described seems reasonable to me for the exper...

Yes, this is the $64,000 question [...] although for me to answer this I'm going to have to pull a dynamics textbook down from the shelf and blow the dust off it Well, the dust was pretty thick on my dynamics book, but I spent a little time investigating the problem and was pleased (if not surprise...

Question, why do you want to remove the axles? Just for observation? Also curious as to the reason. Slow Cure Super Glue. By "slow cure", do you mean the "gel" type? We've used that to permanently fasten nails in slots, and liked the results. It dries almost as fast as regular s...

The cat was not driving the ice cream truck, it was just running into the side of it... OHHHH... :o I totally misunderstood... that of course has much more applicability. ;) This might help get over this small hurdle, since I do agree with most every thing else if the conditions had a certain amoun...

... + translational (linear) kinetic energy + rotational kinetic energy... Thank you for the clarification. I should not have dropped the translational / linear component of the phrase, since both are indeed kinetic energy. :oops: So, for the discussion of frictionless, elastic world effects to be ...

Maybe we are losing the rotational issue by taking away the friction and elastic forces... The intent of temporarily removing friction, spinning wheels, etc. from the physical description is to simply, not complicate, analysis of the rotational issue. my take on this is that without these forces, o...

One would think, however... you are not really changing anything but the vector... you are going straight, now your going right, now your going left, now your going... your rotation is noting more than another direction... I can agree that is a somewhat apt interpretation for the dynamics of point ...

Change in direction is vague... it could encompass pitch, roll, yaw... But some kind of body rotation is meant. :thumbup: For the sake of continuing analysis, let's now limit ourselves to yaw and yaw rate (rather than pitch and/or roll). Wait, I think I disagree... LOL Ummm... the only energy is th...

...what speed would the cat rotate... :thumbdown: The deceleration happens as a result of the friction caused by the collision at the point of vector change. I say don't think of the deceleration because it is a result of the process, we know it comes from the loss of energy... what we are trying t...

My point was that the different MOI had no effect on the direction of reflection of the ball... assuming no other forces where acting on the ball. I am not seeing a clear analogy to the problem being discussed. The car body is being acted upon by forces that don't pass through the center of mass. A...

correct me if I'm wrong but flaws in the track become unmovable objects Let's assume this is so. if the front wheel hits a nick in the center rail which has a say 45 deg deflection that is the way the car is going regardless of where the weight is located [...] If a pool ball bounces of the rail at...

if the cars forward motion get interrupted due to any number of reason and it veers to the right...as you move the mass to the extremities of the car, the amount the mass is rotating, increases... hence you are going to need more energy to correct the vector of the car... Yet if the MOI is higher, ...

Actually the aerodynamics of the thinner body are [junk], the wheels stick out and mess up the air flow [...] I never said that cars got slower as they got thinner, some people seem to be confused because words seem to keep being put in my mouth rather than people directly quoting what I have said....

The owners manual says no but, I don't know of that is the engineer or the lawyer talking. I'm late to this thread, but my understanding is that manufacturers discourage cutting metal and wood on the same machine because sparks from the metal may ignite sawdust in the saw. I have a basic 10" D...

Its not ground breaking. we have been doing it for a long time. If it wasn't faster then why would we be building all these flat cars ? Perhaps my post was unclear. :oops: Thin bodies are indeed fast and nothing new, but I understood Ron suggesting that as a flat car gets thinner, it loses its aero...