Why does a heavier sphere fall faster in a liquid ?

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Discussion Overview

The discussion revolves around the question of why heavier spheres fall faster in a liquid. Participants explore the forces acting on the spheres, including gravitational force, buoyant force, and drag force, while examining the implications of mass on acceleration in a fluid medium.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested, Mathematical reasoning

Main Points Raised

  • One participant questions the premise that heavier balls fall faster, stating that the acceleration should be derived from the equation F=ma, leading to uncertainty about the influence of mass on acceleration.
  • Another participant presents the equation a=g-F_D/m, suggesting that increasing mass affects the forces but does not clarify how it impacts acceleration.
  • A different viewpoint introduces the equation F=ma=mg-F_b-F_d, indicating that for two balls of the same volume but different masses, the larger mass will experience a higher acceleration due to the balance of forces.
  • One participant acknowledges the relationship between mass and drag, noting that while g remains constant, the drag force per unit mass decreases with increased mass, leading to a better understanding of the dynamics involved.

Areas of Agreement / Disagreement

Participants express differing views on the relationship between mass and acceleration in a liquid, with some supporting the idea that heavier spheres fall faster while others remain uncertain about this conclusion. The discussion does not reach a consensus.

Contextual Notes

Participants rely on various assumptions regarding the forces acting on the spheres, including the effects of buoyancy and drag, which may not be fully resolved in their arguments.

KingCrimson
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why do heavier balls fall faster in liquids ?, if F=mg-drag, a heavier ball would have greater mg, but the acceleration is given by F=ma, therefore mg-drag = ma, a = (mg-drag)/m.
I can't see how a heavier ball would fall faster.
 
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You've got ##a=g-F_D/m##. (minus is up here) If you increase mass, g is reduced more or less?
 
F=ma=mg-F_b-F_d where F_b is buoyant force and F_d is drag.

Then; a=g-F_b/m+F_d/m, so if you have two balls of same volume but different mass, the larger mass will have a higher acceleration.
 
Bandersnatch said:
You've got ##a=g-F_D/m##. (minus is up here) If you increase mass, g is reduced more or less?
g is constant, but Fd/m is reduced, I see it now :D thanks.
 

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