Physical interpretation of Force=power/velocity

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Discussion Overview

The discussion centers on the physical interpretation of the equation Force = power/velocity, exploring its implications in the context of constant force, acceleration, and energy transfer in a vacuum. Participants examine the relationships between force, power, and velocity, as well as the conditions under which these relationships hold true.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • One participant expresses confusion regarding the interpretation of the equation, suggesting that constant force should imply constant acceleration, but questions arise when considering the decrease in power as velocity increases.
  • Another participant argues that to maintain a constant force while velocity increases, power must also increase, correcting the misunderstanding about the relationship between power and force.
  • A similar viewpoint is reiterated by another participant, emphasizing the need to increase power as speed increases to keep force constant.
  • Another participant states that if both force and mass are constant, acceleration remains constant, referencing the equation F=ma.
  • An example is provided involving a glider moving at constant velocity, illustrating the relationship between power, drag, and energy transfer in the context of potential energy variation.

Areas of Agreement / Disagreement

There appears to be disagreement regarding the interpretation of the relationship between force, power, and velocity, with some participants asserting that power must increase to maintain constant force, while others express confusion about the implications of constant force on acceleration.

Contextual Notes

Participants discuss the implications of constant mass and force on acceleration, but the discussion does not resolve the underlying assumptions about the nature of power and its relationship to force and velocity.

Who May Find This Useful

This discussion may be of interest to those exploring the dynamics of force, power, and motion, particularly in physics and engineering contexts.

Generic Turtle
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I understand the derivation of the equation Force=power/velocity, but I'm not sure I quite understand the physical interpretation of this. If you had a constant force acting on a particle in a vacuum, then it would gain velocity and as it did so the power would have to go down for the force to be constant. Since the only transfer of energy is into kinetic energy as the particle is in a vacuum. If the power goes down this means the rate at which it gains kinetic energy decreases. This means its acceleration decreases but that doesn't make sense to me, why given a constant force is acceleration not constant. If you combine it with F=ma this implies that the mass of the particle has to increase for this to be the case. Am I intepreting all this correctly?
 
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The physical interpretation is that to apply a constant force and hence a constant acceleration, you must increase the power as the speed increases.

When you look at force=power/velocity and conclude that as velocity increases power must decrease to keep force constant, you have it backwards - to keep the value constant as the denominator of a fraction increases, you have to increase the numerator as well.
 
Nugatory said:
The physical interpretation is that to apply a constant force and hence a constant acceleration, you must increase the power as the speed increases.

When you look at force=power/velocity and conclude that as velocity increases power must decrease to keep force constant, you have it backwards - to keep the value constant as the denominator of a fraction increases, you have to increase the numerator as well.

Oh dear I feel super dumb now :O

Thank you though :)
 
When the force is constant, if the mass is constant too, the acceleration keeps a constant value, since F=ma...

An example of power, velocity and force with constant velocity/zero acceleration is in the case of a glider moving at constant velocity. The force of drag times velocity is the power of the glider; i.e. power=drag*airspeed... Of course, in this case, the energy of the glider comes from the variation of potential energy, as the glider loses altitude... Also, power=weight of the glider*vertical velocity... The drawing shows the forces and the speeds U,V, WW...
9643819798_5639ebe4e0_n.jpg
 

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