Accelerating the mass to the same velocity requires the same energy
regardless of what the surface is doing but wheel drag cannot be totally
ignored.

Why did you suggest that the car is providing the energy for the conveyor?
This would imply wheels with normal friction behavior but a frictionless
conveyor with a brake. The conveyor needs to be frictionless for you theory
that no additional energy is needed but a brake to keep it from being flung
backwards preventing forward motion of the car.

Since the same frictionless conveyor would get dragged along under an
accelerating plane, it seems like a strange experimental model.

A conveyor that is motor driven but controlled makes a more consistent
model.

I agree that very little additional thrust is necessary (either from the
wheels of a car or from the propeller of a plane) to counteract the
counter-moving conveyor. But some additional energy will be needed due to
the additional drag provided by the faster spinning wheels (both for the car
and the plane).

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Travis
"alexy" wrote in message
...
"cjcampbell" wrote:


Tony wrote:
If the car had an airspeed indicator it would, I agree, indicate 60. In
the model I suggested the car is moving to the north at 60, the
treadmill to the south at 60, and the speedometer will indicate 120.

If the car's airspeed indicator said 60 then the speedometer will
indicate 120. But the car would then need to expend the same energy to
accelerate to 60 as it would to accelerate to 120 on a stationary road.
Nope. The same energy as it would take to accelerate to 60 on an
ordinary road, assuming that the mechanical system of the conveyor is
taking care of its motion. The work being done is to accelerate the
same mass to the same velocity in either case. If the car is providing
the energy to move the conveyer (reasonable, if its mass and friction
loads are less than those of the car), how much additional energy it
takes will depend on the conveyer.

An aircraft would need no additional power to accelerate to 60 on a
treadmill.
True. The same laws of physics apply to the car as well.
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