John Eucist Posted February 20, 2017 Share Posted February 20, 2017 Unrelated to eucs. If a car maintains a constant steering angle and turning and there is no new acceleration/power applied (cruising in neutral at any speed) is it possible for the car to complete a circle? Assume that the car will not flip over or skid and that the ground is flat and not banked or that there are any rails. Link to comment Share on other sites More sharing options...
Jag_Rip Posted February 20, 2017 Share Posted February 20, 2017 Its a question of friction I think, theoretically it will drive several circles (e.g. on a Superconductor in a vacuum), but not sure if it completes one full circle in the real world as air and tirefriction will kill a lot of momentum. Link to comment Share on other sites More sharing options...
LEO_LEO Posted February 20, 2017 Share Posted February 20, 2017 I don't understand the question, why not? ...or you talk about of a prefect circle ...or I'm missing something , where is the problem? Link to comment Share on other sites More sharing options...
Mono Posted February 20, 2017 Share Posted February 20, 2017 2 hours ago, LEO_LEO said: I don't understand the question, why not? Because it may run out of kinetic energy before the circle is completed. Link to comment Share on other sites More sharing options...
Mono Posted February 20, 2017 Share Posted February 20, 2017 6 hours ago, John Eucist said: If a car maintains a constant steering angle and turning and there is no new acceleration/power applied (cruising in neutral at any speed) is it possible for the car to complete a circle? I guess the main determining factor is rolling resistance. A related first question which is easier to answer and probably quite helpful to know: what is the coast to stop distance on a straight line as a function of speed? Link to comment Share on other sites More sharing options...
LEO_LEO Posted February 20, 2017 Share Posted February 20, 2017 @Mono in the question I read "if it is possible", and I think this is to exclude the calculation of the friction's coefficients Link to comment Share on other sites More sharing options...
Mono Posted February 20, 2017 Share Posted February 20, 2017 I would think the "is it possible" refers to the free choice of speed and radius and tire and maybe car type, but not the free choice of friction or physical laws. The OP will clarify. BTW, without friction, the question seems to be rather trivial to answer independently of radius and initial speed. Link to comment Share on other sites More sharing options...
John Eucist Posted February 20, 2017 Author Share Posted February 20, 2017 42 minutes ago, Mono said: I would think the "is it possible" refers to the free choice of speed and radius and tire and maybe car type, but not the free choice of friction or physical laws. The OP will clarify. BTW, without friction, the question seems to be rather trivial to answer independently of radius and initial speed. Assume (an unrealistic) scenario of perfect friction between tires and the ground (no skidding) but zero friction everywhere else (wheel bearing, axle, etc.) and no air resistance. However, all other laws of physics applies. Can the car complete a circular turn? Link to comment Share on other sites More sharing options...
Mono Posted February 20, 2017 Share Posted February 20, 2017 1 hour ago, John Eucist said: Assume (an unrealistic) scenario of perfect friction between tires and the ground (no skidding) but zero friction everywhere else (wheel bearing, axle, etc.) and no air resistance. However, all other laws of physics applies. Can the car complete a circular turn? You are looking for the case without rolling resistance? Then I don't see any reason why the car does not continue to roll forever, thereby completing an unbounded number of circles. Or are you interested in the amount of energy lost to deviate from a straight line? I think this would still need to be accounted for under friction/rolling resistance. Or are you interested in the deviation from a perfect circular shape? If you tell us where this question comes from it is probably easier to understand what you are precisely asking for. Link to comment Share on other sites More sharing options...
John Eucist Posted February 21, 2017 Author Share Posted February 21, 2017 6 hours ago, Mono said: You are looking for the case without rolling resistance? Then I don't see any reason why the car does not continue to roll forever, thereby completing an unbounded number of circles. Or are you interested in the amount of energy lost to deviate from a straight line? I think this would still need to be accounted for under friction/rolling resistance. Or are you interested in the deviation from a perfect circular shape? If you tell us where this question comes from it is probably easier to understand what you are precisely asking for. Yes I was more interested in "the amount of energy lost to deviate from a straight line" (but not due to air and rolling resistance). The question doesn't "come from " anywhere. It's just something I thought of and unsure of but felt like I had to find out. So it seems that the answer is that it can make circles forever if no air and rolling resistance. What about in realistic terms of a real car with real-life friction and resistance? Can that typically do one circle under ideal (but realistic) conditions? Link to comment Share on other sites More sharing options...
LEO_LEO Posted February 23, 2017 Share Posted February 23, 2017 I am not sure, but this is my calculation Link to comment Share on other sites More sharing options...
John Eucist Posted February 23, 2017 Author Share Posted February 23, 2017 4 minutes ago, LEO_LEO said: I am not sure, but this is my calculation WOW! Math! So a little over two circles? Is this for the "unrealistic conditions scenario" or the "realistic conditions scenario"? Link to comment Share on other sites More sharing options...
LEO_LEO Posted February 23, 2017 Share Posted February 23, 2017 I don't konw, the friction coefficients are realistics, but I am not sure this is the right calculation method, perhaps there are others importants parameters Link to comment Share on other sites More sharing options...
LEO_LEO Posted February 23, 2017 Share Posted February 23, 2017 ...in school I had ups and downs, it is possible this is a good answer as a reproach, is someone knows something of better... Link to comment Share on other sites More sharing options...
Jurgen Posted February 23, 2017 Share Posted February 23, 2017 a ball on a string atttached to a stick can turn circles without having to rely on friction without friction on the road surface a car will go in a straight line what you looking for is a mag lev kind of device, but this only works on dedicated 'roads' with induction coils in it Link to comment Share on other sites More sharing options...
John Eucist Posted February 23, 2017 Author Share Posted February 23, 2017 1 minute ago, Jurgen said: without friction on the road surface a car will go in a straight line My "unrealistic scenario" was that the tires have perfect friction with the road but everything else in the car like the wheel bearings and axle has zero friction (as well as no air resistance). Gears are no longer engaged ("neutral") when the circle starts. Link to comment Share on other sites More sharing options...
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