Interpreting J/s and J/(s^2): Watts & More

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Discussion Overview

The discussion revolves around the interpretation of the units J/s (Watts) and J/(s^2). Participants explore the implications of these units in terms of power and its rate of change, considering both theoretical and practical applications.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification

Main Points Raised

  • One participant notes that J/s is defined as a Watt and questions the meaning of J/(s^2).
  • Another participant suggests that J/(s^2) could represent the rate at which power increases, although they struggle to find a common example of its application.
  • A different participant describes a scenario where something's power increases by 1 J/s every second.
  • One participant provides a practical example involving a power transmission shaft in a car, initially relating J/(s^2) to the rate of power usage, but later revises their interpretation to suggest it could represent the rate at which power changes over time, particularly in nonuniform conditions.

Areas of Agreement / Disagreement

Participants express varying interpretations of J/(s^2), with no consensus on its practical applications or significance. The discussion remains unresolved regarding the utility of this unit.

Contextual Notes

Some assumptions about the context of J/(s^2) are not fully explored, and the discussion includes conditional reasoning about its interpretation in specific scenarios.

TSN79
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Just trying to interpret some units here. If J/s is Watt, what does J/(s^2) tell me?
 
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W/s is the rate at which power increases. I can't think of an example of where this unit might be commonly used.

Claude.
 
Something's power is increasing by 1 J/s every second.
 
It is the rate at which power is used, as other have said before me. A practical example, you have a power transmission shaft of a car with an applied torque T, with a constant rotational speed, n. You want to determine the power transmitted to the shaft. Then you will have
[tex]\dot{W_{sh}} = 2 \pi \dot{n} T[/tex]

Edit: Oh, I see you said watts/second. Forget what I said above. That would be the rate of the rate at which power is being used. Well, you could change my n dot to an n double dot, where the n double dot is the rotational acceleration I guess. But I can't see any purpose for doing so. I guess you could interpret it as the rate at which the power being transmitted through the shaft is changing with respect to time, if it has a nonuniform speed, n. If you know n double dot, you can integrate to find the power transmission from [tex]t_0[/tex] to [tex]t_1[/tex]

[tex]\dot{W_{sh}} = \int^{t_1}_{t_0} \ddot{W_{sh}} dt = \int^{t_1}_{t_0}2 \pi \ddot{n} T dt[/tex]
 
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