Bender

Seems like a small inconvenience compared to the advantages. And for that fringe group, there is medication to alleviate their motion sickness.

Perhaps. I didn't do the math, nor am I going to invest the time required only to build a worthless gadget. Nevertheless, it might be impossible because the hinge would flip up again before the ball can reach it. Besides, in the video the ball keeps bouncing around, loosing too much energy to keep going for a long time. Even in the ideal case, there is no mechanism to recover the rotational energy of the ball each time it rolls back and forth.

Isn't it enough for those people to be in the front seat and watch the road?

My gut feeling says no, because the hinge should stay up.

I'm willing to bet money that one day there will be selfdriving cars with fitness equipment inside, so you can pretend to walk, run, cycle or row to work.

The biggest hurdle will be juridical. Critics keep shouting about how immoral it is to make a car decide on moral issues. Popular is the artificial situation where the car has to decide between hitting a child or killing the passenger. Nobody ever considers that a human driver doesn't even have the reflexes required to make such decisions. An additional advantage might be that people actually take a bike or go on foot for small distances (<2 km), because waiting 5 min for a car to show up is longer than going by bike.

Nice. What kind of power supply do you use?

Yes

Looks correct. Much easier that way than doing the integration, although the result will be the same.

AC through an electromagnet works too for an alternating magnetic field.

This all sounds like philosophy. Certainly not engineering. btw, only fermions can't occupy the same space. Bosons can.

Except that acceleration might not be constant and the velocity might have a different direction. Claiming that a is "typically" down is a gross simplification, and demonstrates that your deviation is not generally valid. In fact, most of your posts is only valid in very specific situations. So, while I think your intentions are good, I have to agree with studiot.

Correct. It is more efficient to use the battery directly for electrolysis, rather than use it to produce oxygen to drive a fuel cell to do the electrolysis.

Star Trek's warp drive warps space to allow superluminal speeds, if that is the kind of thing you are looking for. I remember an episode of Star Gate where a team is caught near a black hole and the extreme time dilatation causes them to apparently freeze.

Time for an engineer to answer this question No gap needed, just hit it with a hammer. Or put the axis in liquid nitrogen. In engineering, each part has a tolerance. You make it as broad as possible and as tight as necessary. You want to make it broad, i.e. allow for large variations, because then it is as cheap as possible to make. Making two parts exactly identical would require all of the materials to be pure, the crystal latices to be perfect and the atom count to be exact, all of which is practically impossible and insanely expensive to get even close. For the axis and hole, it depends what you want: - if the connection has to be able to transfer force, the axis has to be larger than the hole (force or cooling/heating required for assembly) - if the connection has to be mounted manually, and is not critical, the axis and hole can be about the same, typically h/H tolerances, which means the axis is at most the nominal diameter and the hole is at least the nominal diameter - if the connection has to slide easily, the axis has to be significantly smaller than the hole (but not too small, because than it risks clamping at the edges) Don't mix up engineering with physics . Nothing is exact in engineering; after calculation, we multiply by 2, just to be sure.

Why would the acceleration be constant?

Fill it in into your equation from the first post:[math]r=4\pi R^2=c \cdot \frac {dR^3}{dt}[/math] Or in short: [math]R^2=c \cdot R^2 \cdot \frac {dR}{dt}[/math] After integration : [math]R=R_0 - c \cdot t[/math] Where c are arbitrary constants, unless you want to calculate it for a specific situation, in which case the best way to determine c is probably experimentally. Also, since the rate is negative, c has to be negative. Qualitative prediction: speed will increase exponentially to terminal velocity. Meanwhile terminal velocity decreases, eventually causing the sphere to slow down.

Since dissolution happens at the surface, I would asume that it is related to the surface area, so r=constant.R^2

Are you asuming r to be constant? In that case, finding R(t) is easy. Filling it in your equation with a and v gives at first glance a straightforward differential equation. I would, however, asume r to depend on the surface area of the sphere, which even makes it easier, because in that case R declines linearly in time.

Yes. I double checked with the hand book I use (Giancoli )

You are not the only one making bald claims like that, and most of them turn out to be bs, so the reactions you get are understandable. If you are willing to make the investment: if you have a patent, they are more likely to take you seriously. You could also offer to pay up front for services, so they don't risk that you won't pay after it turns out to be bs. Like suggested earlier: schools are interesting, because even when they don't believe you, it could be an interesting exercise.

Because you integrate over half a circle, which in this case comes down to a multiplication with [math]\pi R[/math] Derivation for full loop

On my phone, right now, but I think the pi is canceled out.

A plastic, low quality, horrible finish combustion engine? I don't think 3D printing is suitable for such a prototype.

Half a loop, so half the flux density of a full loop.