Question #57530

2 Answers

If you are in a moving train relative to train your speed is zero .But relative to earth it may be 80 KM.hour.


If you are living on Earth with reference to your place you are not moving.But Earth is moving at a speed of 30 KM.second in space..The solar system is moving at a speed of 230 KM.second around Milky way..So motion is always relative.

Nov 7, 2017

See explanation


Imagine you're on one of those moving walkways you have between terminals on airports. To anyone standing on the walkway with you, you are not moving. However, to someone standing on the ground just outside, you are moving at some speed (i.e. the speed of the walkway).

Similarly, imagine you're walking backwards on one of those moving walkways (at the same speed as the walkway). Again, to someone standing next to you on the walkway you are moving backwards, but to an observer on the ground, you are not moving at all (and look a bit stupid).

Why is this? It boils down to a concept called relative velocity. The key idea to understand is that all speed is relative to some reference state. So going back to the cases above, the speeds you were walking at were speeds relative to the walkway.

To an observer on the ground, however, you were walking at whatever velocity you were walking at relative to the walkway plus the walkway's velocity relative to the ground to account for the fact that the walkway is also moving relative to the ground.

Self Drawn

So, as you can see, what speeds you perceive are speeds relative to your frame of reference. This is because based on where you're standing, you take in different information about what's about motion.

The viewer on the ground, for example, takes in the fact that the walkway is moving. Similarly, an astronaut would take in the fact that the earth itself is moving in addition to the walkway.

Hope that helped :)