If you are *not* dealing with special relativity and its effects, then the answer becomes far more simple.
If you are not moving and are standing on the ground, then you see a train moving past you a fast speed. In this case, the reference "frame" (not necessarily a point) is you and the object being described is the train.
If you flipped the roles, then it would be someone on the train watching you as the train moves. However, since it is from the train's perspective, it does not appear that the train is moving, but rather that you are moving away from the train, along with the rest of the world that passes the train by. This is described as the train being the reference frame and you would be the object described by the train.
This is, again, just Galilean relativity. Special relativity puts a few twists on it and has some additional effects.
An origin or zero point.
:p hi
Motion is relative. There must be something to compare it to.
That's right, motion cannot be measured unless you have some frame of reference within which to measure it.
One point of view from which to describe motion is the observer's frame of reference. This point of view defines the position and motion of an object relative to the observer. By choosing a specific frame of reference, we can describe how an object moves in relation to that reference point.
frame of reference
An origin or zero point.
:p hi
it would be a because he touches the ground when he walks
Motion is relative. There must be something to compare it to.
That's right, motion cannot be measured unless you have some frame of reference within which to measure it.
One point of view from which to describe motion is the observer's frame of reference. This point of view defines the position and motion of an object relative to the observer. By choosing a specific frame of reference, we can describe how an object moves in relation to that reference point.
It certainly is necessary. Sometimes it may be implied - for example, in practice, quite often planet Earth is used as a frame of reference. But whether it is implied, or explicitly stated, you always need a frame of reference to describe motion, or position.
The two factors that describe motion are thing. :)
Motion is always relative, depending on the reference point. If a tree is the reference point, then the car zooming past will be moving. But, if you use the car as the reference point, then it seems as though the tree is zooming past.
It is called "reference frame"; and yes, that's the basic idea - related to what will you measure movement.
It is called "reference frame"; and yes, that's the basic idea - related to what will you measure movement.