Question

the mass of a cube is 20kg and one of its edge is 3 cm.what is the density ?​

Answer 1

Answer:Since the angle of contact for cube and water is 0

o

, Surface tension provides a downward force to the cube. And for the equilibrium of the cube.

Downward force=upward force

⇒weight + surface tension force=buoyant force

⇒mg+4αT=lα

2

ρg

Here l=distance of the lower face of the cube from the surface of water

⇒l=

α

2

ρg

mg+4αT

⇒l=

3

2

×1×980

20×980+4×3×70

⇒

l=2.3175cm≈2.3cm

Explanation:

We know that density is the ratio of mass and volume of the system. Here the system is cube then the volume of the cube is A3 where A is the edge length of the cube.