ExamBro
ExamBro
AP EAMCET · Maths · Application of Derivatives

If the volume of a sphere is increasing at the rate of \(12 \mathrm{c}. \mathrm{c}. / \mathrm{sec}\), then the rate (in \(\mathrm{sq}. \mathrm{cm} / \mathrm{sec}\) ) at which its surface area is increasing, when the diameter of the sphere is 12 cm is

  1. A \(2\)
  2. B \(3\)
  3. C \(4\)
  4. D \(6\)
Verified Solution

Answer & Solution

Correct Answer

(C) \(4\)

Step-by-step Solution

Detailed explanation

\( r = \frac{D}{2} = \frac{12}{2} = 6 \text{ cm} \) \( \frac{dV}{dt} = 4\pi r^2 \frac{dr}{dt} \) \( 12 = 4\pi (6)^2 \frac{dr}{dt} \implies \frac{dr}{dt} = \frac{12}{144\pi} = \frac{1}{12\pi} \text{ cm/sec} \) \( \frac{dA}{dt} = 8\pi r \frac{dr}{dt} \)…