Can Two Objects Have a Change of Direction Without Speed Change?

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Discussion Overview

The discussion revolves around whether it is possible for two objects to interact in such a way that one object experiences a change of direction without a change in speed. The scope includes conceptual physics and involves interpretations of velocity and speed in the context of motion.

Discussion Character

  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant questions if it is possible for an object to change direction without changing speed, suggesting that a change in direction implies a change in velocity.
  • Another participant clarifies that they meant speed instead of velocity and expresses a belief that a change in direction always accompanies a change in speed.
  • A participant provides the example of circular motion, such as the Earth orbiting the sun, to illustrate that speed can remain constant while direction changes.
  • One participant challenges the circular motion example by arguing that the Earth's velocity changes due to its elliptical path, raising concerns about measuring speed along tangents during directional changes.
  • Another participant attempts to explain that while the component of velocity along the old tangent decreases, the overall speed remains constant due to the introduction of a new velocity component normal to the old tangent.
  • A participant reiterates that an object can only have one speed and expresses confusion over the explanation regarding velocity components, affirming that while velocity changes, speed does not.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between speed and direction change, with no consensus reached on whether an object can change direction without a change in speed.

Contextual Notes

Participants rely on different interpretations of velocity and speed, and the discussion includes assumptions about circular versus elliptical motion that remain unresolved.

Drifter009
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Is is possible when two objects have one interaction, that one object experience only a change of direction and no change in speed?

It seems possible for two objects to have an interaction where there is no change of direction. (Each object has no spin and they are on a co-linear path.) But, I can't think of a way to see an interaction, where one object has a change of direction but no change of speed.
 
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Change of direction implies change in velocity, since velocity is a vector.

I hope you didn't mean speed when you said velocity. In that case, of course it's possible.

Which class are you in?
 
Yes, I mean speed in place of velocity. I will edit it to stop the confusion.

Would it be easy to explain, I am only taking conceptual physics. So, a non-mathematical explanation would be best for me.

This is why I can't think of it any other way:

In order for a mass to change position in a non-linear way, a change in speed must occur which is relative to the original linear path the mass was moving along (or at rest with). So, a change in direction always accompanies a change in speed.
 
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Circular motion, such as the Earth orbiting the sun is an example of the speed remaining constant while direction changes.

Claude
 
I thought the Earth's velocity changes, due to an elipitical path. But, if it were circular I still have a problem. If I choose one tangent along the circular path in which the Earth moves and measure the speed in that direction as the Earth passes. The next moment, the Earth has changed direction. From the new tangent, the speed is the same, but from the old force vector, the speed has decreased.
 
(I am trying my best to understand you and answer.)

The component of the new velo along the old tangent has decreased, but an additional component of the new velo normal to the old tangent has been introduced. The magnitude of the vector sum of these two will remain the same, thus keeping the speed the same at both positions.
 
Drifter009 said:
I thought the Earth's velocity changes, due to an elipitical path. But, if it were circular I still have a problem. If I choose one tangent along the circular path in which the Earth moves and measure the speed in that directionas the Earth passes. The next moment, the Earth has changed direction. From the new tangent, the speed is the same, but from the old force vector, the speed has decreased.
I don't get the bold part, an object can only have one speed. What I think you are doing is looking at the velocity component in a particular direction. Yes the velocity changes, no question, but the speed does not.

Claude.
 

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