Mass & Acceleration: Does Zero Mass Mean Infinite Acceleration?

In summary: With the advent of the molecular model, the mathematics developed in earlier times could be overtaken almost unchanged; however, a lower limit of applicability of the continuum hypotheses had now to be introduced(i.e. continuum mechanics do not accurately describe the behaviour at length scales comparable with the mean free path, for... many small molecules)
  • #1
deadskint
2
0
i have just read while revising for my physics AS exam that

'Mass is the property of an object which resists change in motion'
'An object with larger mass will accelerate less than the object with smaller mass'

does this not imply that an object with zero mass will have infinite acceleration?
and does having infinite acceleration therefore imply the object has the ability to be everywhere at the same time??
 
Physics news on Phys.org
  • #2
Surely that quote should be 'An object with larger mass will accelerate less than the object with smaller mass WHEN SUBJECT TO THE SAME FORCE'

It implies that an object with zero mass COULD have infinite acceleration if it were affected by some force.

The only objects with zero mass are photons and they are not affected by forces- they have 0 acceleration.
 
  • #3
A photon is considered to have an actual mass of zero and a zero rest mass, but when the photon is moving, it assumes an apparent mass due to the velocity (m = E /C2). This apparent mass is significant enough to lend to uncertainties in momentum and position according to Heisenberg.
 
  • #4
quantum mechanic said:
A photon is considered to have an actual mass of zero and a zero rest mass, but when the photon is moving, it assumes an apparent mass due to the velocity (m = E /C2). This apparent mass is significant enough to lend to uncertainties in momentum and position according to Heisenberg.

That is incorrect. A photon has a non-zero (relativistic) mass. Only its rest mass is zero. However this could be a disagreement in terms since the terms "apparent mass" and "actual mass" are not terms that are defined in relativity. At least not in the more well known literature.

Relativistic mass "m" equals the ratio of the magnitude of the particles momentum to its speed. I.e. m = p/v. For a photon v = c. Since E = pc => c/E then

m = p/c = (E/c)/c = E/c2

Pete
 
  • #5
deadskint said:
i have just read while revising for my physics AS exam that

'Mass is the property of an object which resists change in motion'
'An object with larger mass will accelerate less than the object with smaller mass'

does this not imply that an object with zero mass will have infinite acceleration?
and does having infinite acceleration therefore imply the object has the ability to be everywhere at the same time??

Well if we stay at Newtons theory then the answer is clearly No.

F = m * a --> a = F/m if m = 0 we will divide by zero which isn't aloud.

There's no (classical) physical reality of an object with zero mass... it has no physical meaning. Something cannot have an infinite acceleration if it doesn't exist.
 
  • #6
Lorentz said:
There's no (classical) physical reality of an object with zero mass... it has no physical meaning. Something cannot have an infinite acceleration if it doesn't exist.

Sure there is; fluid particles for example.
(They don't have infinite accelerations, though, since the sum of forces acting upon them is zero)
 
  • #7
arildno said:
Sure there is; fluid particles for example.
(They don't have infinite accelerations, though, since the sum of forces acting upon them is zero)

Fluid particles have mass. Anything that has momentum has mass (note: That
s mass, and not rest mass that I'm referring to).

Pete
 
  • #8
Any REAL fluid particle/collection of atoms have mass;
the mathematical abstraction known as a fluid particle (which is what I was talking about) occupies a single, spatial point, with a non-zero density value attached to it.
The mass of a fluid region V is given by:
[tex]M=\int_{V}\rho{dV}[/tex].
Going to the limit [tex]V\rightarrow0[/tex] yields the mass of a single, mathematical, fluid particle
 
  • #9
arildno said:
Any REAL fluid particle/collection of atoms have mass;
the mathematical abstraction known as a fluid particle (which is what I was talking about) occupies a single, spatial point, with a non-zero density value attached to it.
The mass of a fluid region V is given by:
[tex]M=\int_{V}\rho{dV}[/tex].
Going to the limit [tex]V\rightarrow0[/tex] yields the mass of a single, mathematical, fluid particle

You say it yourself. It's a mathematical abstraction... in other words not to be confused with physical reality.

Do note that I don't know anything about the fluid particle you're talking about.
 
  • #10
Lorentz said:
You say it yourself. It's a mathematical abstraction... e.g. not to be confused with physical reality.

Do note that I don't know anything about the fluid particle you're talking about.

You used the term (classical) physical reality, in the first place, and that's what I've referred to.
Up to the development of the atomic theory in the middle 19'th century,
"reality" consisted for physicists in the existence of continua/continuums,
in which such particles were thought to exist.
With the advent of the molecular model, the mathematics developed in earlier times could be overtaken almost unchanged; however, a lower limit of applicability of the continuum hypotheses had now to be introduced
(i.e. continuum mechanics do not accurately describe the behaviour at length scales comparable with the mean free path, for example).
 
  • #11
Lorentz said:
Do note that I don't know anything about the fluid particle you're talking about.

Have you ever calculated in solid mechanics the moment of inertia by integral?
If you have done so, you are using a continuum mechanics model of reality.
 

1. What is the relationship between mass and acceleration?

The relationship between mass and acceleration is described by Newton's Second Law of Motion, which states that the acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass. In simple terms, the more mass an object has, the more force is needed to accelerate it.

2. Can an object with zero mass have infinite acceleration?

According to the equation for acceleration (a = F/m), as mass approaches zero, acceleration approaches infinity. However, in reality, it is impossible for an object to have zero mass because even particles that are considered massless, such as photons, have some amount of mass. Therefore, the concept of an object with zero mass having infinite acceleration is purely theoretical.

3. Is it possible for an object to have zero mass?

No, it is not possible for an object to have zero mass. As mentioned earlier, even particles that are considered massless have some amount of mass. In addition, mass is a fundamental property of matter and cannot be reduced to zero.

4. What would happen if an object had infinite acceleration?

If an object had infinite acceleration, it would experience an infinite force acting on it. This would likely result in the object breaking apart or being destroyed. As mentioned before, the concept of an infinite acceleration is purely theoretical and cannot be observed in the real world.

5. How does zero mass and infinite acceleration relate to the concept of a singularity?

A singularity is a point in space where the laws of physics break down, and the mass and density become infinite. In this theoretical scenario, an object's mass would approach zero as it gets closer to the singularity, causing its acceleration to approach infinity. However, the concept of a singularity is still not fully understood, and it is impossible to observe or create one in the real world.

Similar threads

  • Other Physics Topics
Replies
4
Views
2K
  • Introductory Physics Homework Help
Replies
3
Views
1K
Replies
30
Views
757
  • Other Physics Topics
Replies
19
Views
1K
  • Introductory Physics Homework Help
2
Replies
35
Views
2K
  • Other Physics Topics
Replies
7
Views
1K
Replies
5
Views
1K
Replies
5
Views
787
  • Other Physics Topics
Replies
3
Views
2K
Replies
8
Views
921
Back
Top