How Does Liquid Density and Viscosity Influence Free Fall Braking?

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SUMMARY

This discussion focuses on the influence of liquid density and viscosity on the free fall of objects in a fluid medium. The participants analyze the behavior of a stone (density 2.7 g/ml) and gold (density 19.7 g/ml) dropped simultaneously in liquid glucose (density 1.5 g/ml) within a 1-meter pipe. Key conclusions highlight that density affects buoyancy and that viscosity plays a significant role in the drag experienced by falling objects, ultimately influencing their terminal velocity.

PREREQUISITES
  • Understanding of buoyancy principles
  • Familiarity with the drag equation
  • Knowledge of terminal velocity concepts
  • Basic physics of density and viscosity
NEXT STEPS
  • Research the effects of density on buoyancy in fluids
  • Study the drag equation and its components
  • Explore terminal velocity in different fluid mediums
  • Investigate the relationship between viscosity and free fall dynamics
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Students, educators, and physics enthusiasts interested in fluid dynamics, particularly those exploring the effects of density and viscosity on object motion in liquids.

Arbegator
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TL;DR
If two objects with big diffrence in density but the same size travel through a liquid closer to the density of one of the objects, does it slow down the free fall?
In mine hypothesis I want to slow down free fall for diffrent density objects in liqudies. I have a stone which i roughly a denisty of 2,7 g/ml and gold with 19,7 g/ml. They have the same size. Liquied glucose has the density of roughly 1,5 g/ml. In my example, I drop at the same time in a 1 meter pipe with glucose. How does the density affect the buoyancy with free fall? Does Viscosity matter in this case? Will gold fall faster?
Thank you for your help with trying to sort this out.
 
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Welcome to PF. :smile:

It certainly seems like it will have some effect. Can you post links to the reading you have been doing so far on this question?

Also, is this question for schoolwork? Thanks.
 
Last edited:
Arbegator said:
How does the density affect the buoyancy with free fall? Does Viscosity matter in this case?
Density is important because the driving force is due to the weight, less the buoyancy of the object in the fluid.

Viscosity is critical in that it is part of the drag equation. Terminal velocity is reached when the falling body drag balances the driving force.
https://en.wikipedia.org/wiki/Drag_(physics)#Very_low_Reynolds_numbers:_Stokes'_drag
 
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