Question

Give reasons as to why bodies like cork or wood float in water.

A. They are denser than water
B. They are less dense than water
C. They have the same density as that of water
D. None of these

Answer 1

Hint: This question is based on the concept of buoyancy. The property of the object/bodies to float in the fluid is called the buoyancy. The floatation of the objects/bodies depends on their property called the density. If the density of the object equals that of the density of the water, then, that object floats.

Complete step by step answer:
Archimedes stated about the principle of floatation. According to him, the object/body dropped in the fluid floats in water only if the object/body displaces the amount of water equal to that of the weight of the body/object dropped. The buoyancy is the property of objects/bodies to float or to rise when submerged in the fluid.

If the density of the object/body equals or less than the density of the water, then that object/body floats. If in case, the density of the object/body is more than the density of the water, then that object/body sinks. In this case, the density of the cork or the wood equals the density of the water.

As the reason for the bodies like cork or wood to float in water is, they have the same density as that of water, thus, the option (C) is correct.

Note:
The main points to remember about the buoyancy, that is the law of floatation are: When the buoyant force equals the weight of the body dropped in the fluid, the body floats and remains in the stationary position, when the buoyant force will be more than the weight of the body dropped in the fluid, the body only floats, and does not remain in the stationary position and when the buoyant force will be less than the weight of the body dropped in the fluid, the body sinks or goes down.