Velocity versus Time Graph help?

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Discussion Overview

The discussion revolves around the interpretation of velocity versus time graphs, specifically the meaning of vertical, horizontal, and nearly vertical lines in such graphs. Participants explore the implications of these graphical representations in the context of motion detection experiments.

Discussion Character

  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants assert that a vertical line on a velocity-time graph does not represent a valid function, as it implies an object has every possible velocity at a single moment, which is not physically plausible.
  • Others agree that a horizontal line indicates constant velocity, suggesting that the object moves at a steady speed over time.
  • A participant mentions that a nearly vertical line could represent a very rapid change in velocity, which might avoid the issues associated with a true vertical line.
  • One participant humorously adds a comment about a ball bearing experiencing a rapid change in velocity, illustrating the concept of instantaneous change in a light-hearted manner.

Areas of Agreement / Disagreement

There is general agreement among participants that vertical lines on a velocity-time graph are problematic, but the discussion includes differing interpretations of nearly vertical lines and their implications for rapid changes in velocity.

Contextual Notes

Participants reference a lab context involving motion detectors, but the discussion does not resolve the implications of nearly vertical lines or fully clarify the conditions under which these graphical representations apply.

Who May Find This Useful

This discussion may be useful for students and educators in physics, particularly those studying motion and graph interpretation in kinematics.

lkj6778
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What does a vertical line graph pointing straight up mean? Same for down? What does a horizontal line mean?

y axis=velocity (m/s)

x axis=time (s)
 
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Vertical line doesn't mean anything. It's not even a proper function. f(x) can have only one output per x.
It doesn't make sense intuitively either: one body cannot have simultaneously every possible velocity.

Horizontal means constancy.
 
I was doing a lab with my group where we had to use a motion detector to match the target graphs given. And yes, my axes are correct. (University Physics 1)
 
Velocity=(m/s)

Time=(s)
 
Bandersnatch is correct. A vertical line on a velocity time graph is nonsense. It means that the object has every velocity and only exists for an instant.

A horizontal line means a constant speed.
 
DaleSpam said:
Bandersnatch is correct. A vertical line on a velocity time graph is nonsense. It means that the object has every velocity and only exists for an instant.

A horizontal line means a constant speed.

It could help to add that a 'nearly vertical' line would represent a very rapid change of velocity - thus avoiding the problem of every velocity existing at once. 'Near as dammit', instant change of velocity - as when a ball bearing hits the front of a locomotive. The line is not quite vertical.
 
Right- the ball bearing has just enough time to say "ouch"!
 

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