You are correct, but my intent here -- as was Einstein's in the elevator-in-space example -- was to consider the forces in only a single direction at a time. In the accelerating car example, the "effect" of the acceleration parallel to the ground is the effect analogous to the elevator example; the force of gravity in the car example is perpendicular to the acceleration and therefore has no effect in the former direction.graybear13 wrote:It seems to me that in the accelerating vehicle model there are two foces at work. The vehicles' engine and drive train and Gravity. The vehicle pushing you through Earths Gravity [field].
No, the fact that the seat is pushing you forward means that you're pushing back on the seat. This is Newton's third law of motion. Or perhaps more accurately, you feel the effect of inertia trying to keep you in place (Newton's first law of motion) while the seat pushes you. There is no SWDKWII here.graybear13 wrote:When you feel the vehicle accelerate and the seat pushing you through space you feel the SWDKWII pushing back on you.
Right. With no acceleration (in this dimension), the driver feels no force (in this dimension).graybear13 wrote:Then when you level off and cruise, the G Force goes away...
Unless I'm not interpreting correctly, this is most certainly not true. Your wheels do not negate the pull of gravity. You're not floating at this point in the drag race, are you?graybear13 wrote:the downward push is taken away by your wheels
This "G force" arises from the fact that your inertia tends you to continue to travel straight (Newton's first law of motion), but the seat prevents that from happening; it pushes you the side. Once again, there is no SWDKWII here.graybear13 wrote:you feel no force until you turn the wheel accelerating toward the center of a circle, then you feel the G Force again, the SWDKWII pushing on you.
Because you're changing direction by the same amount in a shorter period of time (or by a greater amount in the same period of time, whichever way you want to interpret the ratio), the seat is exerting more force on you. Again, no SWDKWII.graybear13 wrote:If you hit the gas and turn into an even sharper curve you can really get the G Force going.
I don't know what you mean by "move slightly toward the center," so I can't comment on this. But let me co-opt it for more thought experimentation (backed up by real experimentation):graybear13 wrote:If you accelerate in a jet, level off and then go into a shallow dive and move slightly toward the center you will feel the G Force, the SWDKWII.
The "Vomit Comet" is an airplane that is regularly flown in a way to produce brief periods of "weightlessness" to passengers. It works as such: after climbing to a sufficient altitude, the plane enters a dive that matches the downward acceleration due to gravity. Because the plane floor is "falling" at the same rate as the passengers, the passengers are not pressed against the floor by gravity and perceive weightlessness.
Now consider the Vomit Comet at a constant altitude. Passengers and the plane are experiencing the pull of gravity but the plane isn't falling away, so the passengers feel the effect of gravity's pull.
Now consider the same scenario as immediately above but remove the Earth. With no gravitational pull, passengers experience no weight. But if the plane enters a dive, the passengers (who, you'll remember, are not being pulled down by gravity) will experience a slam against the ceiling of the cabin because the plane is actually moving down around them.
Thus is the elevator example, but in the opposite direction. A plane traveling forward with no Earth below it will have passengers who experience weightlessness, but if the plane enters a climb, the plane lifts the "weightless" passengers from below, just as does Einstein's elevator. The climbing plane (accelerating elevator) is the source of the upward force, providing the sensation of being pulled down against the floor by gravity. There is no SWDKWII.
I agree that there are two apparent forces at work in the lake basket example. The force that the basket exerts on the person has already been explained. The second apparent force is merely an artifact of the density of the movement medium, water. Note that the same idea -- a moving basket containing a person -- in the medium of air doesn't strike us as having the second force. It exists, but the density of the air is so low that this force is virtually insignificant, particularly at low speeds. Any such medium will provide such a force of resistance to motion. Einstein's example sidestepped this additional force by making the elevator impermeable; the air inside the elevator doesn't exert a measurable force because that air is moving along with the elevator instead of through it.graybear13 wrote:I think you have to admit that in the basket modle there are two forces at work also. It seems that pulling the basket releases potential energy that is in the water.
Sure, if we start making stuff up. But then we can pretend whatever the hell we want. This is why we have Occam's razor. You don't believe that your vehicle works because of the drivetrain and because of gremlins under the hood. If I can explain our observations using the principle of relativity or using the principle of relativity and SWDKWII, why the hell should I have SWDKWII in my explanation?graybear13 wrote:The Principle of Relativity does explain our observations but there is always more we can see.