J.C.MacSwell

At some point outside the turbulence the flow essentially remains laminar. Reducing the turbulent regime even slightly will generally reduce the drag. It is not all or none. http://papers.sae.org/2004-01-1145/ From the abstract (which is free) bolded by me: "We demonstrate the interaction of two truck shapes in tandem. Both trucks experience a decreased drag coefficient from the interaction. The degree of drag saving depends strongly upon the drag coefficients of the model trucks in isolation, and upon how the two trucks are arranged. For the two simplest shapes-parallelepipeds with or without partial leading-edge rounding-the total drag saving can range from 10 percent to 40% at a spacing of 2√A (approximately 18 feet at full scale) depending upon whether the lead or the trail parallelepiped has rounding. These two shapes-blunt and rounded-have drag coefficients in isolation of 0.94 and 0.51 respectively, and probably bracket the savings to be obtained for all real truck geometries." Would you really remain the lead goose knowing your buddies are benefiting much more than you are?

From http://en.wikipedia.org/wiki/Drafting_(aerodynamics) Drafting or slipstreaming is a technique where two vehicles or other moving objects are caused to align in a close group reducing the overall effect of drag due to exploiting the lead object's slipstream. Especially when high speeds are involved, as in motor racing and cycling, drafting can significantly reduce the paceline's average energy expenditure required to maintain a certain speed and can also slightly reduce the energy expenditure of the lead vehicle or object.

If you assume because it won't work for aerodynamic shapes, then it won't work for bluff bodies, it might be difficult to convince you.

Sorry. But it does not. Vehicle B can both; benefit from the slipstream of A, and decrease the drag of A, in the right circumstance, by getting close enough to reduce the vacuum on the back of A

There is still a continuos energy requirement to maintain speed. It is just reduced. No laws of physics are broken.

Both can be correct. It depends on the quality of the airflow around the lead vehicle and how the presence of the following vehicle affects it. For the average road vehicle a close following vehicle would usually decrease the drag of the lead vehicle. For a more aerodynamic vehicle with a well designed back end this may not be the case. Often it will depend on the distance the 2 are apart.

All just semantics but for those who insist it is incorrect to consider the dark side of the Earth not a shadow: So when someone mentions your shadow, you immediately look at the dark side of yourself and not the ground? Inconsistently with your opinion of the night side of the Earth, only consider the shadow cast upon the ground? Both, wondering which shadow is being referred to?

I agree. We are in the Earth's shade, but not in or on the Earth's shadow IMO.

unless there is skidding or slipping as imatfaal suggests the material is being stretched by almost 10%. If that is in the elastic range for the material the tension is can be calculated if the coefficient of elasticity is known, but if the material is being drawn or squeezed permanently at one or both sets of rollers then the tension is indeterminate...it would depend on how much of the stretching is permanent, the normal forces at the rollers and properties in the plastic range as well.

Any possibility? If B has same maximum then A must slow down for B to overtake A.

The "special" thing is Special Relativity. The current speed can be well under what would normally yield some other relativistic effects, but even slightly more "ladder in the barn" gives us the magnetic effect. http://en.wikipedia.org/wiki/Relativistic_electromagnetism Of course anything moving with the current would recognize just a static field.

Consider what you described, the spacecraft having the same final kinetic energy, from a different frame. Consider it from a frame in which the spacecraft has much less speed initially...

The Earth is simply not spinning fast enough to overcome the force of gravity, so it does not fly apart, and we do not fly off, or need to hang on.

According to Hoyle... Hoyle's expanding steady state universe, complete with creation field to hold the steady state in spite of expansion, had no need for dust to explain Olber's Paradox. Light from distant stars was cooled and redshifted same as the Big Bang. The problem with the Steady State model was in other areas, particularly in explaining the CMBR.

Assuming the triangle is made of something of even thickness and density it would be at the centroid of the triangle, and at half the thickness. http://www.mathopenref.com/trianglecentroid.html

Watching requires an interaction. On a microscopic level it is insignificant, but at the double slit experimental level it is. At the macroscopic level your bathtub stays at rest ( in the non inertial earth frame), but is buffeted around, shape and all, at the atomic level.

This. Because the = sign is logical shorthand meaning that the equation will balance. The equations need to be balanced to be true, Otherwise they are false.

If I make a statement "half the humans that lived to be 50 years old are alive today, and the other half are deceased" I am most likely off one way or another. 1. On which side am I off? 2. What age should I replace "50 years old" with, to make the statement correct?

Without the magic, if due to some collision or drag an object slows down it would tend to fall to a lower orbit, and in doing so accelerate to a greater than original speed.

The key being proper. There are a lot of elements of recycling programs that miss the mark. Generally the "disorder" they save is important, such as reducing landfill or scarring the environment, but do not necessarily create less entropy than fabricating from new materials.

Just a question on the general trend of % of of mass in galaxies being DM relative to there size. Do the larger galaxies tend to have more (as a percentage) than smaller galaxies? I tried a search but, at least with the keywords I used, I found no answer.

1. Short but incomplete answer is that there was gravitational accretion of enough mass in a sufficiently small area to create it. The potential had to be there. 2. There had to be the same net angular momentum prior. The velocity would have to increase to maintain it, with the energy for the increased velocities coming from the gravitational potential and subsequent accretion 3. No. Stars moving too fast would move outward, slowing them down. The general trend would be gravitational accretion, but faster moving stars would not join in, until slowed by the system, their kinetic energy taken in part by other stars. A few might escape by randomly bucking the general trend, but most would only move outward temporarily. 4. Not sure where the extra mass that is required is, but I don't believe a Super massive Black Hole was necessary to start the process. It probably came about as part of it. 5. I think the "glue" is gravity. The stars are close enough in each arm to be gravitationally bound and not orbit the galaxy independently, yet not so gravitationally bound or so close together that they form a separate orbital system.

What would be the source of the g-forces? The 800km/hr alone won't tell you that. Or do you mean pressure from the apparent 800 km/hr wind? 800 km/hr is certainly well above the terminal velocity of the body when falling (in 1 g) in any position, so without blocking the wind, or securing the rider in some way, he/she would most certainly be blown off

I heard something along those lines about 35 years ago...included in the theory was that they came back as dust balls under your couch

This is true of the PE that remains after terminal velocity is reached. Prior to that, as per DH's post, as soon as any velocity is achieved some of the potential energy starts to be converted to heat, and the remainder accelerates the object to terminal velocity as kinetic energy.