Buoyant force same for all object of same volume?

  • Thread starter david13579
  • Start date
  • #1
20
0
Rank the buoyant forces exerted on the following five objects of equal volume from the largest to the smallest. Assume the objects have been dropped into a swimming pool and allowed to come to mechanical equilibrium. If any buoyant forces are equal, state that in your ranking. (Use only ">" or "=" symbols. Do not include any parentheses around the letters or symbols.)
(a) a block of solid oak
(b) an aluminum block
(c) a beach ball made of thin plastic and inflated with air
(d) an iron block
(e) a thin-walled, sealed bottle of water


My answer? They are all equal since the buoyant force depends only on the volume displaced (whether the buoyant force is stronger or weaker than the weight of the object is irrelevant in this case I think). Cramster also says they are all equal and one of my classmates say it is equal too.

Webassign says they are not equal.
 
Last edited:

Answers and Replies

  • #2
SammyS
Staff Emeritus
Science Advisor
Homework Helper
Gold Member
11,361
1,032
When they achieve mechanical equilibrium, some of them are not fully submerged. Those not fully submerged, displace an amount of water that's' less than for those that stay submerged.
 
  • #3
cmb
906
48
What's the definition of 'buoyant force' intended in the question?
 
  • #4
20
0
Thanks a lot man. So in the end it comes to e=b=d>a>c
 
  • #5
386
5
But don't forget the restriction that they are at mechanical equilibrium. Buoyancy force is only related to volume of water that is replaced. While in equilibrium, some of them are not completely in water, which means no water displaced.
 

Related Threads on Buoyant force same for all object of same volume?

Replies
1
Views
1K
  • Last Post
Replies
2
Views
713
  • Last Post
Replies
5
Views
6K
Replies
4
Views
30K
Replies
2
Views
4K
  • Last Post
Replies
10
Views
4K
  • Last Post
Replies
3
Views
1K
Replies
15
Views
2K
  • Last Post
Replies
7
Views
2K
Replies
1
Views
823
Top