Weight displaced and volume displaced?

  • #1

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 wouldnt be asking

The Attempt at a Solution



i also do not know
 

Answers and Replies

  • #2
150
3
Consider Archimedes' principle and the buoyancy force.
 
  • #3
gneill
Mentor
20,936
2,877
What's are the conditions for neutral buoyancy? What's the (standard) density for air?
 
  • #4
121
4
Think about it this way. The baloon 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 baloon. 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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