In a baseball game the batter hits the ball into center field and takes off for first base. The catcher can only stand and watch
. Assume that the batter runs at a constant velocity. Who measures the proper time it takes for the runner to reach first base, and who measures the proper length between home plate and first base?
The exact time interval between the two different events is the time interval that is measured or calculated by an observer whose position is at rest comparative to the events and watch them taking place at that particular place. The beginning includes the start of the run to first base in the event whereas, the finish of the run to the first a base is the end of the event.
The runner watches the end and the beginning of the event that occurred next to him and hence, the event took place at the same place where the runner was present. The runner is considered at rest relative to his clock.
The exact length of an object is considered to be the length that can be measured by an observer who is believed to be at rest concerning the object.
The catcher is supposed to be at rest relative to the distance between home plate and first base.
