What are 'rods' and 'clocks in relativity?

  • Thread starter Sul
  • Start date
  • Tags
    Relativity
In summary, rods and clocks are used in relativity to establish a coordinate system. They represent length and time, and their measurements can vary depending on the frame of reference. This is due to the principles of relativity which state that the laws of physics are the same in all inertial frames and the speed of light is constant. In special relativity, this leads to the concept of spacetime, while in general relativity, it is shown that mass can curve spacetime.
  • #1
Sul
4
0
Hey I need some help on this. What are 'rods' and 'clocks'. Someone told me it's a coordinate system. I don't understand it. Any help?
 
Physics news on Phys.org
  • #2
Hi Sul,
probably you refer to a statement like "The length of a rod and the speed of a clock are relative" or the like. Am I on the right track?
 
  • #3
As used by Albert Einstein in referance to Relativity, A rod is something that measures length, a clock is something that measures time.
 
  • #4
You use rods and clocks to establish a coordinate system.
 
  • #5
Hi Sul(that's what I'm called as well)...

Relativity uses the concepts of rods and clocks instead of meter or seconds because every person, according to reltivity, has his own time...time, length and mass are relative...thats why its more appropriate to use rods and clocks...
 
  • #6
Stranger, I not sure you have it right there.
For example in one reference frame a second might be defined as so many cycles of a certain atom clock, in another reference frame it could be defined as the same number of cycles of the same design of atomic clock. The clocks moving relative to each other would just not agree with each other, but they could each still define a second as the same thing.
 
  • #7
meter or seconds

Thanks Dave...I know that I shouldn't have written this down...
 
  • #8


Originally posted by Sul
Hey I need some help on this. What are 'rods' and 'clocks'. Someone told me it's a coordinate system. I don't understand it. Any help?

In relativity there are two principles

(1) The laws of physics are the same in all inertial frames of referance

(2) The speed of light is indendent of the source in an inertial frame of referance

When put together it can be shown that
(1) a moving clock runs slower than an identical clock which is at rest
(2) a moving rod is shorter than an identical rod which is at rest

The slowing of clocks implies that the slowing of the clock has to do with the slowing of time itself. And same with the shortening of the rod - space itself has contracted.

Hence special relativity is the theory of space and time i.e. Space-Time!

Then there's General Relativity which gets more complicated. It can be shown that in the mass can curve spacetime!

Pete
 
  • #9


Originally posted by Sul
What are 'rods' and 'clocks'. Someone told me it's a coordinate system.
A “rod” is just a ruler. A “clock” is an instrument that measures elapsed time. See http://www.everythingimportant.org/relativity to understand how rods and clocks are used to comprehend spacetime.
 

1. What are rods in relativity?

Rods in relativity refer to physical objects used to measure distances in the theory of special relativity. They are typically represented as long, thin objects that can be moved and compared to other rods to determine the length of an object or distance between two points.

2. What are clocks in relativity?

Clocks in relativity refer to devices used to measure time in the theory of special relativity. They are typically represented as a mechanism with a constant rate of motion, such as a pendulum or the vibration of atoms, that can be compared to other clocks to determine the duration of an event or the passage of time.

3. How are rods and clocks related in relativity?

Rods and clocks are related in relativity because both are used to measure physical quantities, specifically distance and time, which are relative to the observer's frame of reference. The measurements made by rods and clocks are used to calculate the effects of time dilation and length contraction in special relativity.

4. Why are rods and clocks important in relativity?

Rods and clocks are important in relativity because they provide a way to measure the effects of time and distance in different reference frames. They allow for the calculation of relativistic effects, such as time dilation and length contraction, which are crucial for understanding the theory of special relativity and its implications for our understanding of space and time.

5. Can rods and clocks be used to measure time and distance in all situations?

No, rods and clocks can only be used to measure time and distance in situations where the effects of relativity are significant. In everyday life, the effects of relativity are negligible and traditional methods of measurement are sufficient. However, in extreme situations, such as near the speed of light or in strong gravitational fields, rods and clocks must be used to accurately measure time and distance.

Similar threads

  • Special and General Relativity
3
Replies
84
Views
4K
  • Special and General Relativity
2
Replies
35
Views
2K
  • Special and General Relativity
Replies
16
Views
597
  • Special and General Relativity
2
Replies
62
Views
4K
  • Special and General Relativity
Replies
15
Views
754
  • Special and General Relativity
2
Replies
59
Views
2K
  • Special and General Relativity
Replies
21
Views
1K
  • Special and General Relativity
2
Replies
50
Views
2K
  • Special and General Relativity
Replies
14
Views
2K
  • Special and General Relativity
Replies
25
Views
847
Back
Top