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Concepts Of Physics MCQ Edition [Volume 1]
Exam
Concepts Of Physics MCQ Edition [Volume 1]
Subject
Physics
Chapter
Some Mechanical Properties of Matter

Concepts Of Physics MCQ Edition [Volume 1] · Physics · Some Mechanical Properties of Matter

Determine the surface energy of water contained in a cylindrical...

Determine the surface energy of water contained in a cylindrical vessel with a radius of 6.0 cm6.0 \text{ cm}. The surface tension of water is 0.075 J/m20.075 \text{ J/m}^2.

Options

  1. A2.8×10−2 J2.8 \times 10^{-2} \text{ J}
  2. B8.5 J8.5 \text{ J}
  3. C2.7×10−4 J2.7 \times 10^{-4} \text{ J}
  4. D8.5×10−4 J8.5 \times 10^{-4} \text{ J}

Correct answer

D. 8.5×10−4 J8.5 \times 10^{-4} \text{ J}

Step-by-step solution

The surface energy of a liquid is given by the product of its surface tension and the area of its free surface.

The free surface of water in a cylindrical vessel is circular. The area of this surface is:

A=πr2A = \pi r^2

Given the radius r=6.0 cm=6×10−2 mr = 6.0 \text{ cm} = 6 \times 10^{-2} \text{ m}, the area is:

A=π×(6×10−2)2=36π×10−4 m2A = \pi \times (6 \times 10^{-2})^2 = 36\pi \times 10^{-4} \text{ m}^2

The surface tension of water is T=0.075 J/m2T = 0.075 \text{ J/m}^2.

The surface energy EE is:

E=T×AE = T \times A

E=0.075×36π×10−4E = 0.075 \times 36\pi \times 10^{-4}

E=2.7π×10−4 JE = 2.7\pi \times 10^{-4} \text{ J}

Using π≈3.14\pi \approx 3.14:

E≈2.7×3.14×10−4 J=8.478×10−4 JE \approx 2.7 \times 3.14 \times 10^{-4} \text{ J} = 8.478 \times 10^{-4} \text{ J}

Rounding off, we get:

E≈8.5×10−4 JE \approx 8.5 \times 10^{-4} \text{ J}
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