Is the train an inertial reference frame if luggage starts sliding forward?

Click For Summary

Homework Help Overview

The discussion revolves around the concept of inertial reference frames in the context of a train moving on a horizontal track, where a piece of luggage begins to slide toward the front of the train. Participants explore the implications of this observation on the train's status as an inertial reference frame.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss the definition of an inertial reference frame and the conditions under which it is valid. They question whether the motion of the luggage indicates acceleration of the train and explore the relationship between acceleration and the behavior of objects within the train.

Discussion Status

The discussion is active, with participants raising questions about the definitions and implications of inertial frames. Some participants suggest that the luggage's movement indicates a lack of constant speed, while others reflect on personal experiences with acceleration in vehicles to relate to the problem.

Contextual Notes

There is an ongoing examination of the definitions and assumptions related to inertial reference frames, particularly in relation to the motion of the luggage and the train's acceleration. Participants are considering the nuances of motion and acceleration without reaching a definitive conclusion.

physicsgurl12
Messages
184
Reaction score
0

Homework Statement



You are in a train traveling on a horizontal track and notice that a iece of luggage starts to slide toward the front of the train. from this observation you can conclude that this train is not an inertial reference frame because it is slowing down.

Homework Equations



true

The Attempt at a Solution

its true but why??
 
Physics news on Phys.org
Uhh... what's the definition of an inertial reference frame?
 
a FRAME REFERANCE THAT DESCRIBES TIME AND SPACE
 
it has no acceleration
and for the crate to move there must be deacceleration
 
Hmm, let's take a look at wikipedia.
It says (skipping a couple of paragraphs):

"In an inertial frame, Newton's first law (the law of inertia) is satisfied: Any free motion has a constant magnitude and direction"

Does the piece of luggage have a motion with constant magnitude and direction?


physicsgurl12 said:
it has no acceleration
and for the crate to move there must be deacceleration

Turning this around: if the train deaccelerates, the crate would move.
What if the train accelerates?
 
if the train accelerates it would stay still
 
physicsgurl12 said:
if the train accelerates it would stay still

Have you ever been standing in a train or bus that accelerates?
If you have, did you have trouble to keep standing?

Or in a car, can you feel it if the car accelerates?
 
um it was a while algo, but is it like when it takes off it acclerates so you kinda jerk forward?
 
Well, if a train accelerates, you are jerked forward.
And if you don't compensate you'll be flying to the back of the train.

In a car you are pressed against the back of the seat.
And when a car is braked, you'd fly forward except that the safety belts keep you in place.
 
  • #10
okay so for the luggage to slide forward you must be accelerating
 
  • #11
Well... a piece of luggage would not try to compensate...
 
  • #12
so it would just slide back then
 
  • #13
Yes - if the train were accelerating, the piece of luggage would slide back.

What was the question again?
 
  • #14
why can you conclude it is not an initial referance frame?
 
  • #15
physicsgurl12 said:
why can you conclude it is not an initial referance frame?

Not exactly...

The question starts by stating that the piece of luggage starts moving forward.
... and it ends with the question whether the train is slowing down.

Does it?
 
  • #16
yes.because its the opposite of it moving forwards
 
  • #17
Right! :smile:

As for the inertial reference frame question:

Does the piece of luggage have a motion with constant magnitude and direction?
 
  • #18
yeah?
 
  • #19
Well, it's rather important that the piece of luggage "starts" moving.
That means that its speed (or motion) is *not* constant...
 

Similar threads

Understanding meaning of inertial reference frames
  • · Replies 2 ·
Replies
2
Views
2K
Undergrad Energy and reference frames
  • · Replies 87 ·
3
Replies
87
Views
6K
What Forces Act on a Train Moving South in Edmonton?
  • · Replies 12 ·
Replies
12
Views
3K
Pendulum hung from the ceiling of a train
  • · Replies 18 ·
Replies
18
Views
3K
Solving the Train Length Ratio Puzzle
  • · Replies 1 ·
Replies
1
Views
2K
High School Solving Doubts about Simultaneity Exp. in Special Relativity
  • · Replies 13 ·
Replies
13
Views
3K
Inertial frame where rods have same length
  • · Replies 4 ·
Replies
4
Views
2K
Two masses connected by spring rotate around one axis
  • · Replies 2 ·
Replies
2
Views
3K
High School A difficulty with the equivalence of all inertial reference frames
  • · Replies 28 ·
Replies
28
Views
3K
Undergrad Simultaneity: Train and Lightning Thought Experiment
  • · Replies 136 ·
5
Replies
136
Views
16K