Can something moving linearly without rotation have anguar momentum?

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Discussion Overview

The discussion centers around the concept of angular momentum, specifically whether an object moving linearly without rotation can possess angular momentum. The context involves a scenario from a physics textbook where a sticky putty is thrown at a stationary wheel, prompting questions about the conservation of angular momentum in this situation.

Discussion Character

  • Conceptual clarification
  • Technical explanation

Main Points Raised

  • Some participants propose that even though the putty is moving in a straight line and has no spin, it can still possess angular momentum when considered with respect to a reference frame.
  • It is noted that the angular momentum of a system is the sum of the angular momenta of its individual components, implying that the putty contributes to the overall angular momentum of the system.
  • Participants clarify that angular momentum is defined relative to a chosen origin, and thus a point mass moving straight can have angular momentum based on its distance from that origin.

Areas of Agreement / Disagreement

Participants generally agree that linear motion can result in angular momentum when considered from a specific reference point, but the discussion does not resolve all nuances regarding the implications of this concept.

Contextual Notes

The discussion does not address potential limitations or assumptions regarding the choice of reference frame or the conditions under which angular momentum is conserved.

nabeel17
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I was doing a question in Taylor book (example 3.3) where a sticky putty is thrown at a stationary wheel. To solve it we use conservation of angular momentum. What I am confused about is that the wheel is initially at rest and has no angular momentum initially. But when the putty is thrown at it the wheel starts spinning and gains angular momentum. Since angular momentum must be conserved (external torque is 0 so angular momentum conserved) there must be some inital angular momentum from the putty.

So my question is even though the putty is thrown in a straight line and has no spin or rotational motion, it still posses angular momentum?
 
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nabeel17 said:
So my question is even though the putty is thrown in a straight line and has no spin or rotational motion, it still posses angular momentum?
Yes.

Even a point mass has angular momentum with respect to some reference frame. That essentially is how angular momentum is defined. The angular momentum of a system of particles is the sum of the angular momenta of the individual particles.
 
D H said:
Yes.

Even a point mass has angular momentum with respect to some reference frame. That essentially is how angular momentum is defined. The angular momentum of a system of particles is the sum of the angular momenta of the individual particles.

Ok so with respect to some origin, a point mass will have angular momentum given by rxp where where r is the distance from the origin. Even if it appears to be going straight with no rotation correct? So angular momentum is always defined with respect to an origin
 
Exactly.
 
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