Velocity versus speed and philosophizing thereof

  • Context: High School 
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Discussion Overview

The discussion revolves around the conceptual differences between velocity and speed, particularly in an educational context. Participants explore how to clarify these concepts to students, focusing on definitions, the role of direction, and the implications of displacement versus distance.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants emphasize that velocity is a vector quantity that includes direction, while speed is a scalar quantity that does not.
  • One participant suggests that students should be asked to differentiate between displacement and distance, highlighting that displacement involves direction.
  • Another participant notes that students may focus on the formula for velocity without fully grasping the concept of direction, indicating a potential misunderstanding.
  • There is a suggestion to ensure students understand the differences between displacement, distance, and distance traveled before discussing velocity.
  • One participant proposes asking students about scenarios where displacement returns to zero, which could further illustrate the concept.

Areas of Agreement / Disagreement

Participants generally agree on the importance of clarifying the distinction between velocity and speed, but there are differing views on how best to approach this clarification and the level of understanding students currently possess.

Contextual Notes

Some limitations include potential misunderstandings of the terms involved, reliance on formulas without conceptual understanding, and the informal use of "velocity" in everyday language.

Head_Unit
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I asked a class of students what the difference was of velocity versus speed. The answer I was looking for was "direction" i.e. one is a vector. But a number of them said "Velocity is displacement divided by time, and speed is distance divided by time." Ignoring the second half of that assertion, I'm not sure what to say about the statement…because that is exactly what the equation says! (V=deltaX/t). To complicate things, "velocity" is ofttimes used colloquially and not in such a picky way. What would you say to the students who responded like this?
 
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I would ask them what the difference is between displacement and distance. If the answer included that displacement involves direction (ie moved 10 metres to the East) whereas distance doesn't (ended up 10 metres from where it started), then I think the answer is good. They would still have captured the idea that velocity involves direction whereas speed does not.
 
In this case, displacement is "how far you are from where you started" so I don't believe they are thinking about direction very explicitly. Probably they are just looking at the formula --> I can't say the answer is wrong, but it's not really right. I guess one thing I could do is to dissect that and say "note that displacement implies a DIRECTION"...
 
I think that before discussing velocity you should make sure they understand the difference between displacement, distance and distance traveled.
 
Perhaps ask them about situations where after some time the displacement is zero again.
 

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