J
JasonSB
Guest
OK, so you donât know the difference between velocity and acceleration.
Yeppers!! âTo Walkâ is to change velocity by acceleration.
âTo walk at exactly 4 km/hâ means to change position at a constant velocity of 4 km/h. If the velocity is constant then there is no acceleration, as acceleration is nothing more and nothing less than the time derivative of velocity. The time derivative of a constant is zero.
Sure â itâs disproved by the very fact that I said âto walk at exactly 4 km/hâ. How the person came to be walking at exactly 4 km/h is beyond the scope of the original example. The fact is that there is nothing stopping them from walking at exactly 4 km/h for the duration of the example and if they are walking at exactly 4 km/h then there is no acceleration by definition.Care to disprove it?
If they were to stop walking or to walk at a speed other than exactly 4 km/h then there would have to be an acceleration. But there wasnât.
None of this actually matters, of course, which is why my later example incorporated acceleration in an attempt to bypass this pointless discussion. Itâs a shame you completely ignored it and instead chose to argue basic physics â possibly because itâs the only thing you thought you understood, which is also a shame, because itâs wrong, but I guess it helps me prove my point.
No. The only reason it is impossible is because of Relativity. Without Relativity kinetic energy does not tend to infinity as the speed of light is approached. Itâs a consequence of Relativity.The above statement, that I answered, is not an argument of relativity. It is a statement of kinetic energy impossibility, as we know it.
I should also point out that the kinetic energy you are talking about is observer-dependent. From the point of view of an observer in an inertial reference frame where the object is at rest (e.g. the train), its kinetic energy is zero. It can accelerate in that reference frame perfectly normally. Itâs only an outside observer travelling at a different speed who will see differently and itâs really a consequence of time dilation.
No. It is most certainly not impossible for the passenger to walk forwards in the train at 4 km/h as stated in my original problem. Even if we start walking as part of the problem, so that there is an acceleration at the beginning, it makes no difference â the passenger can still walk from the rear to the front of the train at 4 km/h even while the train is travelling at 2 km/h below the speed of light.It is false, because of one thing.
It is a matter of kinetic energy which goes to infinity at the speed of light, and can never be reached by acceleration, as we know it, now.
What is false is the conclusion that if the train is travelling at 2 km/h below the speed of light and the passenger is walking 4 km/h faster than the train then the passenger must be travelling 2 km/h above the speed of light. They are not. They are actually travelling barely more than 2 km/h below the speed of light while at the same time they are walking 4 km/h faster than the train.
Objects of mass can not accelerate at the speed of light.
Let alone, â2km/h above the speed of lightâ⌠remember infinity ].
Brilliant.No need to argue relativity in your above statement. No need for outside observers. It makes no difference what they observe.![]()
Itâs pretty obvious you donât know anything about Relativity. Youâre relying on a result of Relativity that you must have heard from somewhere (that you apparently donât even know is a result of Relativity) to claim that somethingâs impossible but youâre completely missing the point of why. There is nothing stopping the passenger from walking from the back of the train to the front no matter how fast itâs going. They never exceed the speed of light no matter what reference frame you use.
Itâs also pretty obvious that my hypothetical example of how not being able to explain a scientific theory to you does not mean anything about the correctness of that theory actually turns out to be a pretty good real-life example, too.
Oh, I am. That doesnât mean I can explain complicated scientific theories to people unequipped to understand them, and that doesnât mean those theories are wrong. Which was kind of my point.I thought you were a âscientistâ?![]()