Question

A hollow container has an external volume 1000cm cube and 100g .
(a)What mass of metal must be placed inside it so that it sinks in water???
(b)Explain why it would not sink in water if the same mass metal calculated above , were tied to the outside of the container??

Answer 1

Answer:

The density of material is is ρ

The hollow sphere will float if its weight is less than the weight of the water displaced by the volume of the sphere This implies mass of the sphere is less than that for the same volume of water. Now, mass of spherical cell

m

1

=4πR

2

×t×ρ

While the mass of water having same volume

m

2

=

3

4

πR

3

×ρ

g

=

3

4

πR

3

where, ρ

g

= density of water 1 g.cm

−3

For the floatation of sphere,

m

1

≤m

2

4πR

2

×t×ρ≤

3

4

πR

3

⇒tρ≤

3

R

⇒t≤

3ρ

R

Answer 2

Answer:

≤100g................,