What is the difference between relative and absolute motion?

In summary: Can someone please provide a summary that is not a reiteration of what has already been said?In summary, rotation is relative to some frame of reference. Acceleration and related forces can be considered to be absolute if not considering general relativity issues.
  • #1
Shahin.Omar
36
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!
 
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  • #2
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.
 
  • #3
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?

:)
 
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  • #4
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.
 
  • #5
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?
 
  • #6
Just to add, the definitions required is for bodies *not* approaching the speed of light.
 
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  • #7
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.
 
  • #8
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)?
 
  • #9
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!
 
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  • #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.
 
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Related to What is the difference between relative and absolute motion?

Question 1: What is the difference between relative and absolute measurements?

Relative measurements are based on a comparison to a reference point or scale, while absolute measurements are based on a fixed standard or unit of measurement.

Question 2: Can you provide an example of a relative measurement?

One example of a relative measurement is the height of a person, which can be measured in relation to the average height of the population or compared to the height of another person.

Question 3: How are relative and absolute measurements used in scientific experiments?

Relative measurements are often used to compare different variables or conditions within an experiment, while absolute measurements are used to determine exact quantities or values.

Question 4: Is one type of measurement more accurate than the other?

It depends on the context and purpose of the measurement. Both relative and absolute measurements have their own advantages and limitations, and the choice of which one to use will depend on the specific needs of the experiment or study.

Question 5: Are there any situations where relative measurements are preferred over absolute measurements?

Relative measurements are often preferred in cases where the exact value or quantity is not as important as the comparison between different variables or conditions. They can also be useful when there is no fixed standard or unit of measurement available.

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