Is Velocity in Angular Motion Referring to Tangential or Angular Speed?

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Discussion Overview

The discussion revolves around the interpretation of velocity in the context of angular motion, specifically whether the term "velocity" refers to tangential speed or angular speed. Participants explore the distinctions between these two concepts and how they are represented in problem statements, particularly in beginner physics contexts.

Discussion Character

  • Conceptual clarification
  • Debate/contested
  • Homework-related

Main Points Raised

  • Some participants note that when a problem states a velocity of 4 m/s, it is likely referring to tangential speed, as angular velocity is measured in 1/s.
  • There is a suggestion that in uniform circular motion, the average speed can be calculated based on the circumference and time taken, which may imply tangential speed.
  • One participant expresses uncertainty about how to determine if the velocity mentioned in a problem is tangential or angular, seeking clarification on the terminology used.
  • Another participant emphasizes the relationship between angular and tangential speeds, stating that if the units are in m/s, it indicates tangential speed.
  • There is a reiteration that tangential speed is often used in problems involving circular motion, while angular speed is expressed in radians/sec or degrees/sec.

Areas of Agreement / Disagreement

Participants generally agree that velocity stated in meters per second likely refers to tangential speed, but there remains some uncertainty about how to definitively identify it in problem statements. Multiple viewpoints exist regarding the clarity of terminology in physics problems.

Contextual Notes

Some participants highlight the importance of units in distinguishing between tangential and angular speeds, but there are unresolved questions about how to interpret specific problem statements without additional context.

oneplusone
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Hello,

I was solving some problems today. Sometimes the wording is something like this:

A ball attached to a string is traveling around a circular track with velocity [itex]4[/itex] m/s.
etc.


When it says the velocity is 4 m/s , does this mean the tangential, or angular velocity?
what is the distinction?

Thanks.
 
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oneplusone said:
When it says the velocity is 4 m/s , does this mean the tangential, or angular velocity?
Angular velocity is not measured in m/s, but in 1/s.
 
If you are doing uniform circular motion (beginner's physics), most likely the problem is talking about avg. speed. For example, if the circle has a circumference of 5 m and the ball traveled around it in 2 seconds, the avg. speed is 2.5 m/s.
 
JeweliaHeart said:
If you are doing uniform circular motion (beginner's physics)
Hello,

Yes, I'm doing beginners physics. I'm just having trouble finding if the object the problem mentions is traveling at a TANGENTIAL speed or ANGULAR speed. Like in the OP, how would you know that the velocity mentioned is tangential velocity?
Thanks.
 
oneplusone said:
Hello,

Yes, I'm doing beginners physics. I'm just having trouble finding if the object the problem mentions is traveling at a TANGENTIAL speed or ANGULAR speed. Like in the OP, how would you know that the velocity mentioned is tangential velocity?
Thanks.

The speed Jewelia worked out is the tangential speed. For uniform circular motion, the tangential speed is constant (as well as the angular speed).

Remember the relation between angular and tangential speeds: [itex]v = \omega r[/itex], so if it has units of [itex]m/s[/itex] it refers to the tangential speed.
 
Last edited:
Hello,
So does this mean whenever a problem says "an object moves with speed, s, in a circular path" the speed is the TANGENTIAL speed?I'm not sure how to phrase my question clearer.
 
Look at your units. Most likely, the problem is referring to tangential speed.

tangential speed is often written in meters/sec.

angular speed has units of radians/sec or degrees/sec.
 

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