Question

A block of wood is floating in the water in a closed vessel as shown in the figure. The vessel is connected to an air pump. When more air is pushed into the vessel, the block of the wood floats with (neglect compressibility of the water)

A. larger part in the water
B. smaller part in the water
C. some part in the water
D. at some instant it will sink.

Answer 1

Hint: This question can be solved or understood by using Pascal's law and simple definition of buoyancy force. This will give us the condition of the wood block.

Formula used:
$P=\dfrac{F}{A}$

Complete step by step solution:

First let’s see Pascale's law for better understanding of this solution.
$\to $ Pascal's law:-
The external static pressure applied on a confined liquid is distributed or transmitted evenly throughout the liquid in all the directions.
So we know that pressure is,
 $P=\dfrac{F}{A}$
Where, P = pressure
F = force
A = area.
Now as we see from the definition when we provide air through an air pump it will be equally distributed in the vessel as we can see in the figure.
But now let’s come to the point that this wood block is submerged or not as we know that this air pressure which is equally distributed will not affect the buoyancy force because the pressure difference for the upthrust force still remains the same.
The reason behind that is that the air density is still lower than water or liquid.

So our correct answer is option (c) the same part in the water. Therefore there will be no change in the condition of the wood block.

Note:
As an approach to solve this question we saw the definition of Pascal's law and the concept of the buoyancy force which is used to reach the correct solution of this question.