Frames of Reference on Top of a Moving Train

• ZachBirnski
In summary: The object would go the same relative distance as it would if thrown from a person standing on motionless ground, disregarding air resistance of course.
ZachBirnski
When an object is thrown by someone standing on top of a moving train, which variations of "frames of reference" would apply? (i.e. inertial, non-inertial, etc.) How would this principle work? (The object would go the same relative distance as it would if thrown from a person standing on motionless ground, disregarding air resistance of course)

You'll have to clarify the question. If the train is accelerating relative to the Earth, it is a non-inertial frame.

Brian_C said:
You'll have to clarify the question. If the train is accelerating relative to the Earth, it is a non-inertial frame.

The train isn't accelerating; its velocity is constant. More focus is placed on the action of the object being thrown forward in respects to the moving train than the motion of the train.

It is inertial motion and the principle of relativity applies: you can play "catch" in the cabin of a moving train exactly the same if it is moving or not.

russ_watters said:
in the cabin of a moving train

Or on top of the train, provided of course that you're not going fast enough to make the wind a factor.

ZachBirnski said:
The train isn't accelerating; its velocity is constant.
I never thought of this before, but this particular comment snagged my attention. To some extent, the train is, in fact, accelerating. It is following the curvature of the Earth, which means that its path is actually circular rather than linear. I might be misunderstanding some official terminology, but that constant 'downward' change of vector implies to me an acceleration.

ZachBirnski said:
The object would go the same relative distance as it would if thrown from a person standing on motionless ground, disregarding air resistance of course

Assume a person on the platform uses energy E to throw a ball in the direction the train is heading and the ball lands on the ground 100 feet in front of him.
Suppose again that a person standing on the train throws a ball in the same direction, using the same amount of energy to do so. Relative to the person on the train, the ball falls to the ground far closer than 100 feet.
In light of this, how can the object "go the same relative distance..."?

1. What is a frame of reference?

A frame of reference is a set of coordinate axes used to describe the position and motion of objects in space. It provides a point of view from which an observer can measure or describe the position, velocity, and acceleration of an object.

2. How does the frame of reference change on a moving train?

On a moving train, the frame of reference changes because the train is in motion. This means that the position, velocity, and acceleration of objects on the train will be described differently depending on whether they are observed from the perspective of someone on the train or someone on the ground.

3. Why is it important to consider frames of reference on a moving train?

Considering frames of reference on a moving train is important because it allows us to accurately describe the motion of objects on the train from different perspectives. This is especially useful when trying to understand the relationship between objects on the train and objects on the ground.

4. What are some common frames of reference used on a moving train?

Some common frames of reference used on a moving train include the train itself, a stationary object on the train (such as a seat or window), the ground outside the train, and an observer on a stationary platform watching the train go by.

5. How does the concept of relative motion apply to frames of reference on a moving train?

The concept of relative motion applies to frames of reference on a moving train because the motion of objects on the train will appear different depending on the frame of reference from which they are observed. This means that an object may appear to be moving relative to one frame of reference, but stationary relative to another.

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