show that if a particle is in a stationary state at a given time it will always remain in a stationary state.

Physics

1 answer:

Lena [83]3 years ago

8 0

That statement is impossible to show, demonstrate, or prove.

A big part of the reason for the inability to show it is that the statement is ... prima facie, pro bono, and habeus corpus ... wrong, and as false as the day is long.

Although I am certainly far from what you might call a 'particle', I think I can show, using myself, that the statement is false:

As we speak, I am sitting, <u><em>in a stationary state</em></u>, before my computer. It is my intention, and I fully believe it will come to pass, that in a few seconds, my fingers may move to operate one of the letter keys, or my hand may reach out to snag my coffee cup, or my entire being may arise from my place and go into the kitchen for a bowl of oatmeal. At the INSTANT that any of these events takes place, the statement will have been proven false.

QED

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a student pushes a box with a total mass of 50kg. what is the net force on the box if it accelerates 1.5 m/s^2?

Zielflug [23.3K]

F=mass times acceleration so multiple 50 by 1.5 and u get 75

5 0

3 years ago

FIGURE 1 shows part of a mass spectrometer. The whole arrangement is in a vacuum. Negative ions of mass 2.84 x 10-20 kg and char

yuradex [85]

Yes, the ions can exit slit P without being deflected, if the electric field strength is 170.6 N/C

Explanation:

When the ions are inside the container, they are subjected to two forces, with directions opposite to each other:

The force due to the electric field, whose magnitude is $F_E=qE$ , where q is the charge of the ion and E is the strength of the electric field
The force due to the magnetic field, whose magnitude is $F_B=qvB$ , where v is the speed of the ions and B is the strength of the magnetic field

The ions will move straight and undeflected if the two forces are equal and opposite. By using Fleming Left Hand rule, we notice that the magnetic force on the (negative) ions point upward: this means that the electric field must be also upward (so that the electric force on the ions is downward). Then, the two forces are balanced if

$F_E = F_B$

which translates into

$qE=qvB\\\rightarrow v = \frac{E}{B}$

Therefore, if the speed of the ions is equal to this ratio, the ions will go undeflected.

We can even calculate the value of E at which this occurs. In fact, we know that the ions are earlier accelerated by a potential difference $V=-3000 V$ , so we have that their kinetic energy is given by the change in electric potential energy: