Question

Fill in the blank.
An iron cube and a copper cube of the same weight but different volumes are fully immersed in a liquid; they will experience _______ buoyant force.
A.) Same
B.) Different
C.) No
D.) All the above may be correct

Answer 1

Hint: The magnitude of buoyant force acting on a body depends on the density and volume of the body and acceleration due to gravity. The buoyant force on a submerged body increases with increases in these parameters.

Step by step answer:
When a solid body is submerged in any liquid then it experiences an upward force. Archimedes gave a principle which gives magnitude of this force. According to Archimedes principle, the magnitude of force that the body experiences when submerged in a liquid is equal to weight of the liquid displaced by submerging the body. This force is called buoyant force or the upthrust of the liquid and this phenomenon is called buoyancy.
The buoyant force is given by the following expression:

${F_B} = V\rho g$

Where V = volume of liquid displaced by the object
$\rho$ = density of the object submerged
g = acceleration due to gravity

This means that buoyant force is directly proportional to the density of the object.

We are given an ice cube and a copper cube which have the same mass but different densities. This implies that the buoyant force acting on them will be different when they are submerged fully in a liquid.

So, the correct answer to our question is option B.

Note: Along with the density of the object, the buoyant force also depends on acceleration due to gravity at a place which means how much gravity is acting on the object while it’s submerged. The value of g changes with height and also depth and the buoyant force will be different at different places on Earth.