J.C.MacSwell

e) I would question what's in my tea and biscuits.

In the reverse direction there would be just one velocity at some point during the approach that would result in the ball coming to absolute rest at the top. There would be many more where it would "seem" perfectly stationary for some duration before heading off in some direction, the duration and direction being fixed by the mathematics of the idealized case. So Newtonian Mechanics might not be perfectly time reversible after all…but you might have to wait around for an eternity to "prove it".

That's all frame dependant. Newton's Laws are not (inertial) frame dependant.

Not sure if this is being missed, but once in the dynamic friction range in any direction it is in that range in any other direction, until it comes to a stop. (there are transitional effects, but not significant here)

Could they not give the tiny pilots some kind of IQ test? If they do average, or worse, they are unlikely to be super intelligent.

It's OK to make jokes about variables, they are flexible enough to hold there own (you don't fix variables, they fix you), but no one here is going to laugh while you pick on constants.

You take the best physical experimental team in the World to set up the experiment under the most consistent conditions they can muster and have them run it 1,000 times and none of the trials will be duplicated. It is chaotic. Chaotic does not mean it does not follow the rules of physics (not saying you are making that claim) nor does it mean that it is not deterministic. It means the outcomes diverge significantly over time with the slightest change. Someone with Parkinson's generally has control independent of a minor fluctuation that happened previously (convergence), though it can certainly lead to divergence if, say, an accident occurred that would not have otherwise.

In a nutshell (over simplified) Speed...generally with speed to the power of 2. Direction...drag opposing the velocity direction, lift perpendicular, by pressure distribution Orientation determines the direction of the lift, as it determines the pressure distribution over the surface depending on the shape Shape is affected by the pressure distribution and gravity on the flexible sheet It's not deterministic. The slightest imperceptible change will effect a significant change in outcome over even very short periods of time. It is deterministic macroscopically that the paper will land on the floor, but that is not the topic. With respect to the path and erratic movements it is chaotic. Edit: Checked my definitions... It is in fact chaotic, but could be considered deterministic as well http://en.wikipedia.org/wiki/Chaos_theory I still don't think it is deterministic based on quantum considerations which I believe is enough on it's own to lead to non deterministic outcomes (due to significant enough subsequent divergence in the time frames involved) even at that level but I could be wrong/stand to be corrected.

Right. Backward in the reference frame of the platform.

While the force of gravity on the paper is constant, the aerodynamic forces vary considerably with it's speed, direction, orientation, and shape. So it somewhat oscillates in movement, but in a chaotic and seemingly random way.

One thing to keep in mind is that the rest mass of a system is greater than it's constituent parts. So adding energy does not require an increase in particles to effect an increase in mass. For example, if you heat up a gas cloud, the number and rest masses of the individual particles will not have changed, but the individual velocities will have on average increased. This will add to the rest mass of the system. Note that the rest masses of the individual particles are all relative to their individual reference frames, and the rest mass of the system is taken wrt the system as a whole.

One caution is that statement is somewhat ambiguous. It is sliding backwards relative to the non inertial frame of the merry go round, not relative to the ground, the ground being what is referenced in the "direction of spin" of the merry go round. You have of course made it clear with the remainder of the description...as long as you don't go back to using the non inertial frame and conclude that there must be a real force pushing the jar outward.

That's correct. When that force is strong enough to overcome the maximum static friction it moves in the direction of the combined vectors. A free body diagram helps to see what will occur.

It reverses as soon as the applied force up the slope becomes greater than the gravitational component down the slope, while still in static range, and the mass moves when the applied force becomes greater than the gravitational component and maximum static friction force combined.

If the liquid is frictionless, isn't the viscosity assumed to be negated?

"If your theory is found to be against the second law of thermodynamics, I give you no hope; there is nothing for it but to collapse in deepest humiliation." Sir Arthur Eddington, Nature of the Physical World (1927) "The pursuit of perpetual motion is equivalent to dreaming about an everlasting tin of beer." String Junky, The Original Science Forums (2015) The alcohol content may be different, but the message remains the same.

When accelerating the spin, it can rise opposite the acceleration. This direction can become inward with the first part of the rotation, before it becomes outward...and can slosh around before becoming primarily outward.

In the Atlantic Provinces, University of New Brunswick in Fredericton, Dalhousie in Halifax, and I think Memorial in St. John's Newfoundland all have good Engineering programmes, though I am not sure about robotics in particular.

I think the OP might be referring to the extra dimensions posited in Kaluza-Klein theory or String theory. Interesting question. I would expect if they were expanding or contracting (assuming they exist) the laws of physics would be changing over time, unless they were all somehow geared to orchestrate or compensate each other in some manner.

I started to laugh at that, but stopped as I was heading for the ceiling

That sucker's pretty big... Agree with acme, an almost negligible gain from no air resistance, and you still have the extra weight and bulk of the suit to overcome

From the original post...I skimmed through but did not see it covered and had not seen this thread prior to today (IIRC) Does an electron in free fall radiate? (My thought would be no) Does an electron forced to stay at rest in a gravitational field radiate? (It must...correct?? or am I off base?) So I'm thinking electrons do not radiate due to gravitational forces (alone)

Hi KC No one is trying to imply cat's are smarter. It is just that they have evolved to land on 4 feet very effectively and very efficiently. A simpler method of merely rotating the tail does not achieve the same result. Their instinctive method is actually very clever and a little complicated, even if they have no real understanding of what they are doing.

Here you go again...

I'll go with the cats, that control the precession about other axes while counter rotating about the main one, enabling them to land on all four feet in best orientation. You can't do that by simply spinning your tail.