Quote:
Originally Posted by Thymeclock
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Let's say you live at sea level. And you drive to a place that is 100 or more miles away that is at a much higher elevation, more than 1000 feet. You will burn more fuel going there than coming back, assuming that all other factors are equal.
Now, if you are fortunate enough that you leave with your vehicle empty (including a half-empty gas tank) and return with a full tank of gas and a 1000 pound load in it from that higher elevation, it will work to your advantage. It's all downhill from there, essentially, no matter how you slice it.
But if you have to leave with a full load, driving to a higher elevation, and you must return with it empty, the prevailing forces will be working against you.
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So in brief the argument is that the gain in potential energy difference may offset the loss due to increased rolling resistance. I suppose that may be possible in steep grades. I would be interested in seeing a calculation of the example of 1000 feet drop over 100 miles.
Quote:
Originally Posted by AeroModder
Now, is the increase in rolling resistance enough to counteract inertia? Or does the increased resistance to change speed overcome the rolling resistance?
I'm pretty sure that the slight increase in rolling resistance is not enough to overcome inertia.....
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Remember the "inertia", or more precisely, the kinetic energy, comes from burning fuel. More fuel will be burnt to reach the same speed with more mass. There is no "free lunch", just net loss due to increased rolling resistance. On a flat road at least.