Question

An object weighs 10 N in air. When immersed fully in water, it weighs only 8 N. The weight of the liquid displaced by the object will be

• A. 2 N
• B. 8 N
• C. 10 N
• D. 12 N

Answer 1

The correct option is A

2 N

Step (1) Given:

The weight of the object in the air $=10N$

The weight of the object in liquid $=8N$

Step (2) Statement of Archemedes' Principle:

Archimedes’ principle states that the upward buoyant force that is exerted on a body immersed in a fluid, whether partially or fully submerged, is equal to the weight of the fluid that the body displaces. The buoyant force acts in the upward direction at the center of mass of the displaced fluid.

Step (3) Finding the weight of the liquid displaced by the object:

According to Archimedes' principle,

The weight of the displaced liquid = weight of the object in the air – weight of the object in liquid

$$\begin{gathered} =10N–8N \\ =2N \end{gathered}$$

Hence, the weight of the liquid displaced by the object is 2 N.