What does relative mean in physics?

[jamesfirst]

What does relative mean..!

I still don't understand the meaning of relative.

I cannot breach onto the concept of Einstein's Principles of Relativity without knowing the meaning of it!

I searched the internet but all of the definitions listed makes no sense to me..

Can somebody define what relative means in a simple statement..


Kind regards, James

 

[PhanthomJay]

At speeds far less than light speed, suppose Jack and Jill are both sitting in the front seat of a car moving at 30 m/s relative to the ground. But their speed relative to each other is zero. You can replace the term 'relative' with the phrase 'with respect to' . Or say Dick is running east toward Jane at 5 m/s with respect to (relative to) the ground, and Jane is running west toward Dick at 6 m/s with respect to the ground, then relative to each other, Jane is running west toward Dick at 11 m/s relative to Dick, and Dick is running east toward Jane at 11 m/s relative to Jane. This simple addition of velocities breaks down at speeds that are a significant fraction of lightspeed, due to time dilation and length contraction at those high speeds.

 

[jamesfirst]

At speeds far less than light speed, suppose Jack and Jill are both sitting in the front seat of a car moving at 30 m/s relative to the ground. But their speed relative to each other is zero. You can replace the term 'relative' with the phrase 'with respect to' . Or say Dick is running east toward Jane at 5 m/s with respect to (relative to) the ground, and Jane is running west toward Dick at 6 m/s with respect to the ground, then relative to each other, Jane is running west toward Dick at 11 m/s relative to Dick, and Dick is running east toward Jane at 11 m/s relative to Jane. This simple addition of velocities breaks down at speeds that are a significant fraction of lightspeed, due to time dilation and length contraction at those high speeds.

Ah in the respect to.


Nice. I understand now.