What is the difference between relative and absolute motion?

  • Thread starter Thread starter Shahin.Omar
  • Start date Start date
  • Tags Tags
    Absolute Relative
Click For Summary
Relative motion refers to the position and velocity of an object as observed from a specific frame of reference, while absolute motion is characterized by a lack of reference, allowing for quantifiable measurements. The discussion highlights that while linear motion at constant velocity is inherently relative, acceleration can be considered absolute under certain conditions, excluding relativistic effects. The rotation of the Earth can be described both relatively and absolutely, with the absolute value quantifiable through inertial forces. The definitions of relative and absolute motion are primarily accepted in classical mechanics, with questions raised about their applicability in quantum mechanics and general relativity. Ultimately, the thread concludes that while relative motion can be quantified, absolute motion remains elusive and challenging to define distinctly.
Shahin.Omar
Messages
36
Reaction score
0
Hello!

Can someone explain to me what is relative, and what is non-relative or absolute?
As I understand linear motion at constant velocity is called relative.
Can you give more such examles for me to understand why something is called relative?

Cheers!
 
Physics news on Phys.org
Position and velocity are relative to some frame of reference. Acceleration and related forces can be considered to be absolute if not considering general relativity issues.

Getting back to position and velocity, say you're standing at some spot on the earth. The Earth is rotating, so except at the poles, it's surface is moving (with respect to it's own axis), the Earth is orbiting the sun, the sun is orbiting the center of our galaxy, and our galaxy is moving with respect to others.
 
Jeff Reid said:
Position and velocity are relative to some frame of reference. Acceleration and related forces can be considered to be absolute if not considering general relativity issues.

Please can you exlain it a little bit more, and what is accepted in physics today?

Is rotation of Earth on its axis relative?

And can I define 'relative' as an event/attribute that requires a frame of reference for it to be detected?

:)
 
Last edited:
Shahin.Omar said:
Is rotation of Earth on its axis relative?
You can express rotation relative to something. But you can also quantify rotation's absolute value, which doesn't work for linear motion at constant velocity.
 
A.T. said:
But you can also quantify rotation's absolute value, which doesn't work for linear motion at constant velocity.

Whats rotation's absolute value, how do I quantify it?
Can you help me define relative and absolute so I can tell what is relative and what is not?
 
Just to add, the definitions required is for bodies *not* approaching the speed of light.
 
Last edited:
Shahin.Omar said:
Whats rotation's absolute value, how do I quantify it?
You can measure the inertial forces and calculate the rate of rotation from it.
Shahin.Omar said:
Can you help me define relative and absolute so I can tell what is relative and what is not?
Relative means it was compared to some arbitrary reference. Absolute means no arbitrary reference was used.
 
A.T. said:
Relative means it was compared to some arbitrary reference. Absolute means no arbitrary reference was used.

Can you also tell me the exact extent to which the above definitions are correct (apart from the term I used)?
 
Shahin.Omar said:
Can you also tell me the exact extent to which the above definitions are correct
Can you ask a physically relevant question?
 
  • #10
A.T. said:
Can you ask a physically relevant question?

Sorry for any ambiguity!

What I wanted to know is if the definitions you gave are universally accepted by all theories (like Quantum Mechanics and General Relativity) or they are only correct from Classical Mechanics point of view?

If it is only accepted in classical mechanics, can you tell me what is the accepted definition in GR or QM?

Hope this clarifies any doubts.

:)
 
  • #11
:smile:
 
  • #12
A.T. said:
You can express rotation relative to something. But you can also quantify rotation's absolute value, which doesn't work for linear motion at constant velocity.

I have not had a final reply to this thread, I did not form my question correctly in the beginning, not that it was easy, sometimes you don't know how to put it?

I would like to close this thread with final conclusion; while we can quantify what is relative we cannot quantify what is absolute, if we could quantify what is absolute there would no difference between relative and absolute.

A.T. was wrong in saying, "But you can also quantify rotation's absolute value."

Cheers guys!
 
  • #13
The only one who is wrong here is you, Shahin.
 
  • #14
D H said:
The only one who is wrong here is you, Shahin.

No problem, except you cannot prove it. Be happyy!

Cheers!
 
Last edited:
  • #15
Shahin.Omar said:
A.T. was wrong in saying, "But you can also quantify rotation's absolute value."

That's not true. You can. Repeating that you can't doesn't make it less true.

This thread is demonstrating rotation - it's going around in circles.
 
Last edited:

Similar threads

High School Rotation is absolute, linear motion is relative?
  • · Replies 74 ·
3
Replies
74
Views
4K
Graduate Effects of a spatially nonuniform diffusion parameter
  • · Replies 6 ·
Replies
6
Views
2K
Undergrad Determining a stationary point of reference to base all absolute motion
  • · Replies 57 ·
2
Replies
57
Views
3K
Undergrad Understanding the historical shift away from absolute simultaneity
  • · Replies 25 ·
Replies
25
Views
901
High School Brainstorm: Is absolute zero relative
  • · Replies 23 ·
Replies
23
Views
4K
Undergrad Why can coefficient "a" between spacetime intervals depend on velocity between systems?
  • · Replies 18 ·
Replies
18
Views
1K
High School Moist air - does it rise or drop?
  • · Replies 42 ·
2
Replies
42
Views
12K
Undergrad Trying to understand the inner workings of a solar cell
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad The Einstein Clock aka Light Clock
  • · Replies 34 ·
2
Replies
34
Views
2K
High School What is Absolute Time and Space?
  • · Replies 5 ·
Replies
5
Views
2K