Fluid Statics

Practice Questions:

Question 1: easy

A cubical box of wood of side 30 cm weighing 21.6 kg floats on water with two faces horizontal. Calculate the depth of immersion of wood.

1. 30 cm

2. 24 cm

3. 20 cm

4. 15 cm

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Question 2: easy

Given below are two statements:

Assertion (A): A hydrogen-filled balloon stops rising after it has attained a certain height in the sky.

Reason (R): The atmospheric pressure decreases with height and becomes zero when maximum height is attained by balloon.

1. Both (A) and (R) are true and (R) is the correct explanation of (A).

2. Both (A) and (R) are true but (R) is not the correct explanation of (A).

3. (A) is true but (R) is false.

4. Both (A) and (R) are false.

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As the balloon rises, the density of air decreases, leading to a decrease in buoyant force until it equals the weight of the balloon, so it stops rising. Thus, Assertion is true. However, atmospheric pressure does not become zero at this height, making Reason false.

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Question 3: easy

The atmospheric pressure at a place is \(10^5\text{ Pa}\). If liquid of specific gravity equal to 2, be employed as the barometric liquid, the barometric height will be (\(g = 10\text{ m/s}^2\))

1. 5 m

2. 3.2 m

3. 7 m

4. 4.5 m

View Answer

Using the relation \(P = \rho g h\), where density \(\rho = 2 \times 10^3\text{ kg/m}^3\) (specific gravity is 2). Substituting the values: \(10^5 = 2 \times 10^3 \times 10 \times h\). Solving for \(h\) gives \(h = 5\text{ m}\).

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