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To: Myrddin

Remember that first day of calculus class? The lower bound is zero, really. Because of conservation of momentum, the force required to stop is the same and the lower bound is zero also, really.

I did not misunderstand and all pertinent stipulations for the statement to be true were made in the statement(except for elevation change as someone pointed out).

Because you threw out the statement that there was some lower bound of energy for transportation without really thinking about what affects that lower bound, you are limitted in seeing potential solutions.

When I go to work I burn 3 gallons of gasoline. If I drove 55 mph, I would probably burn 2 gallons. If I trimmed 3,000 lbs off my vehicle and made it very aerodynamic, I would burn about a gallon. If I was just moving my body, it would only take a few ounces.

Why does my car weigh 4000 lbs, two reasons.

First I am pushing around a very heavy engine and transmission and a frame capable of carrying that engine. What if I don't need a heavy engine and transmission.

Second, is safety, steel is very effective for safety but by no means is required. Soldiers don't wear steel helmets because it is too heavy and there is material that provides more safety with less weight.

Actually, there is a third reason. Steel is cheap.

If you break down where your energy is going, you can figure out what you need to use and what you are using just because that is how your dad did it.

Remember the lower bound is really zero. Every bit of energy above that buys you something but there may be a smarter way of doing it.


226 posted on 01/01/2007 6:31:09 PM PST by dangerdoc (dangerdoc (not actually dangerous any more))
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To: dangerdoc

So we have a kevlar car that cannot pull a trailer?

And it costs 200K?

I'll suffer with only 300hp and pay the higher cost of fuel as these silly clown cars will get no work done.


232 posted on 01/01/2007 7:13:29 PM PST by Eaker (You were given the choice between war & dishonor. You chose dishonor & you will have war. -Churchill)
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To: dangerdoc
Remember that first day of calculus class? The lower bound is zero, really. Because of conservation of momentum, the force required to stop is the same and the lower bound is zero also, really.

It's only zero if the upper bound is zero too. There is no free lunch. If you move from a state of rest, energy is expended. If you are in motion, you must expend energy in an equal and opposite direction to return to a state of rest. Energy from gasoline puts you in motion. Frictional energy on the brake rotor/drum is expended to return the vehicle to a state of rest. If you happen to be rolling uphill when you want to stop, the energy is transformed to gravitational potential energy.

When I go to work I burn 3 gallons of gasoline. If I drove 55 mph, I would probably burn 2 gallons. If I trimmed 3,000 lbs off my vehicle and made it very aerodynamic, I would burn about a gallon. If I was just moving my body, it would only take a few ounces.

The limit doesn't go to zero. The fuel itself has mass and chemical potential energy. It is also dependent on nascent oxygen to convert the chemical potential into useful energy. ΔG = ΔH - TΔS. You will be producing heat and gas along the way.

233 posted on 01/01/2007 7:14:30 PM PST by Myrddin
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