Can an object that is producing radiation, have an acceleration but not move

[blastoise]

Can an object that is producing radiation, have an acceleration but not move...

Hi,

I took a quiz today and one question was ,

"Which of these would produce radiation"
a) a moving particle
b) accelerating particle
c) DC current
d) a magnetic field (can't remember this)


The answer is B. But, I would argue that an accelerating particle must be moving hence the answer would be A and B. Was told no not true and the answer is B.


How is it possible for a particle to accelerate and not be moving in ℝ^3

position f during time t is

f(t) = location at time t
f'(t) = velocity
f''(t) = acceleration >> which produces radiation

if f'(t) = 0 or a, where a is a constant then then f''(t) = 0, so no radiation is produced if f'(t) = 0 or a.

But... f''(t) =/= 0 => f'(t) = anti derivative f''(t)=> f'(t) =/= 0 hence it is moving

Can anyone think of an example where particle in space has an acceleration not equal to 0, but does not have any movement?

 

[Matterwave]

Motion is always frame dependent.

If you are in a reference frame accelerating along with the particle, then the particle is not moving in your reference frame.

We usually don't like to use accelerating reference frames because inertial reference frames are easy to deal with (and SR prohibits accelerating reference frames from being global like inertial ones), but they are not invalid frames of reference.

For example. I would say that me sitting in my chair is "not moving". But I am accelerating along with all the other objects on the Earth's surface due to both the rotation of the Earth, and the orbit of the Earth. It's simply that I am in a non-inertial reference frame.

 

[blastoise]

Motion is always frame dependent.

If you are in a reference frame accelerating along with the particle, then the particle is not moving in your reference frame.

We usually don't like to use accelerating reference frames because inertial reference frames are easy to deal with (and SR prohibits accelerating reference frames from being global like inertial ones), but they are not invalid frames of reference.

For example. I would say that me sitting in my chair is "not moving". But I am accelerating along with all the other objects on the Earth's surface due to both the rotation of the Earth, and the orbit of the Earth. It's simply that I am in a non-inertial reference frame.

If the particle was said to be in a vacuum would the frame of reference argument still hold?

What about if the particle is spinning would it still be moving?

 

[haruspex]

Hi,

I took a quiz today and one question was ,

"Which of these would produce radiation"
a) a moving particle
b) accelerating particle
c) DC current
d) a magnetic field (can't remember this)

The answer is B. But, I would argue that an accelerating particle must be moving hence the answer would be A and B. Was told no not true and the answer is B.

How is it possible for a particle to accelerate and not be moving

You're missing the point. A particle can be moving but not accelerating. In that case it would not produce radiation. The question could be made clearer: "which will necessarily produce radiation", whereas you're reading it as "which could produce radiation".

However, the answer given is still not right. Only a net acceleration of charge will produce radiation.
Accelerating isolated proton or electron: yes.
Accelerating neutral atom or molecule: no.
Internally vibrating N2 or O2 molecule: no.
Internally vibrating electrovalent bond: yes.
Internally vibrating polar molecule (like CO2, H2O): yes.
DC: no.
AC: yes.
Etc.

 

[sardar]

I would like to clarify that it is not possible for an object to have an acceleration but not move. Acceleration is defined as the rate of change of velocity, which means that if an object has an acceleration, it must also have a change in velocity. In order for an object to have a change in velocity, it must be moving. Therefore, it is not possible for an object to have an acceleration but not move.

Regarding the question about producing radiation, both a moving particle and an accelerating particle can produce radiation. This is because radiation is a form of energy, and any change in energy can result in radiation being emitted. So, both a moving particle and an accelerating particle can produce radiation.

In the case of an accelerating particle, the radiation is produced because the particle is gaining or losing energy as it accelerates. This change in energy results in the emission of radiation. However, even if the particle is not moving in ℝ^3, it is still experiencing a change in energy and therefore can still produce radiation.

I cannot think of an example where a particle in space has an acceleration not equal to 0, but does not have any movement. In space, there are various forces acting on particles, such as gravity and magnetic fields, that can cause acceleration. However, even if the particle appears to be stationary, it is still experiencing a change in energy due to these forces and can still produce radiation.

In conclusion, an object cannot have an acceleration but not move, and both a moving and accelerating particle can produce radiation. It is important to understand the definitions and principles of physics to accurately answer questions like these.