• Support PF! Buy your school textbooks, materials and every day products Here!

Hollow sphere in water

  • Thread starter kristjan
  • Start date
  • #1
2
0

Homework Statement


Hollow iron sphere is half submerged in water.Sphere has outer diameter of 10 cm. Calculate thickness of the wall , when the iron density is 7.9 g / m3.
I get answer 0.11cm, book says that it is 0.22cm.

Homework Equations


[/B]


The Attempt at a Solution


First i found buoyant force F=ρgV/2 where ρ is density of water and V is volume of a sphere.
Then I found mass of a sphere : ρgV/2=mg
m=0.26 kg
I know density of iron ,so: 7900=0.26/v where v is volume of the wall
(v= volume of outside sphere - volume of inside sphere.)
From there I get thikness of the wall to be 0.11cm.
 

Answers and Replies

  • #2
Bystander
Science Advisor
Homework Helper
Gold Member
5,173
1,173
  • #3
TSny
Homework Helper
Gold Member
12,404
2,840
I get answer 0.11cm, book says that it is 0.22cm.
Your method looks correct. I agree with your answer of .11 cm.
 
  • #4
Bystander
Science Advisor
Homework Helper
Gold Member
5,173
1,173
Someone made my "intuitive" error while re-writing the exercise for the "n-th" edition; agreed, 0.11 cm.
 

Related Threads on Hollow sphere in water

Replies
16
Views
796
Replies
4
Views
480
  • Last Post
Replies
7
Views
3K
  • Last Post
Replies
14
Views
58K
Replies
29
Views
775
  • Last Post
Replies
4
Views
9K
  • Last Post
Replies
5
Views
5K
  • Last Post
Replies
0
Views
2K
  • Last Post
Replies
2
Views
29K
Replies
1
Views
4K
Top