Weight displaced and volume displaced?

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Homework Help Overview

The problem involves a hot air balloon that is hovering, with a focus on understanding the concepts of weight and volume of displaced air. The original poster seeks to determine the weight of the displaced air and the volume of that air based on the balloon's total weight.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants discuss Archimedes' principle and its relevance to buoyancy. Questions are raised about the conditions for neutral buoyancy and the standard density of air. There is an exploration of the implications of the balloon hovering and the relationship between the weight of the balloon and the weight of the displaced air.

Discussion Status

The discussion is ongoing, with participants providing insights and prompting further inquiry into the principles at play. Some guidance has been offered regarding the relationship between weight and displacement, but no consensus or resolution has been reached.

Contextual Notes

Participants note the need for additional information, such as the density of air, to progress in solving the problem. The original poster expresses uncertainty about the problem's requirements and their own understanding.

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Homework Statement



you are hovering (no acceleration) in a hot air balloon of total weight (balloon+load+hot air) 18,000 N

a) what is the weight of displaced air?

b) what is the volume of displaced air?

Homework Equations



if i knew i wouldn't be asking

The Attempt at a Solution



i also do not know
 
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Consider Archimedes' principle and the buoyancy force.
 
What's are the conditions for neutral buoyancy? What's the (standard) density for air?
 
Think about it this way. The balloon is hovering. It's not going up or down. Suppose it was slowly going down. Why would it be going down? Because every time it went down by 1mm, something heavy would be closer to the ground. That could be you in the balloon. But you're not going down. That means something equally heavy must have to go up when you go down. That's the displaced air. It must have the same weight as the thing that displaced it, because if it was lighter you'd go down, and if it was heavier you'd go up.

If you know what it weighs and you know its density, you can figure out it's volume. Do you know the density of air?
 

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