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The volume of the spherical ball is incr...

The volume of the spherical ball is increasing at the rate of `4pi` cc/sec. Find the rate at which the radius and the surface area are changing when the volume is `288pi` cc.

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To solve the problem step by step, we will follow the given information and apply the necessary mathematical formulas. ### Step 1: Identify the given information We are given: - The rate of change of volume, \( \frac{dV}{dt} = 4\pi \) cc/sec. - The volume at a specific moment, \( V = 288\pi \) cc. ### Step 2: Use the volume formula for a sphere The formula for the volume \( V \) of a sphere in terms of its radius \( r \) is: \[ V = \frac{4}{3} \pi r^3 \] ### Step 3: Set up the equation for the given volume Substituting the given volume into the formula: \[ 288\pi = \frac{4}{3} \pi r^3 \] We can simplify this equation by dividing both sides by \( \pi \): \[ 288 = \frac{4}{3} r^3 \] ### Step 4: Solve for \( r^3 \) Multiply both sides by \( \frac{3}{4} \): \[ r^3 = 288 \times \frac{3}{4} = 216 \] ### Step 5: Find the radius \( r \) Taking the cube root of both sides: \[ r = \sqrt[3]{216} = 6 \text{ cm} \] ### Step 6: Differentiate the volume with respect to time Now, we differentiate the volume formula with respect to time \( t \): \[ \frac{dV}{dt} = 4\pi r^2 \frac{dr}{dt} \] ### Step 7: Substitute known values into the differentiated equation We know \( \frac{dV}{dt} = 4\pi \) and \( r = 6 \): \[ 4\pi = 4\pi (6^2) \frac{dr}{dt} \] This simplifies to: \[ 4\pi = 4\pi (36) \frac{dr}{dt} \] Dividing both sides by \( 4\pi \): \[ 1 = 36 \frac{dr}{dt} \] ### Step 8: Solve for \( \frac{dr}{dt} \) \[ \frac{dr}{dt} = \frac{1}{36} \text{ cm/sec} \] ### Step 9: Find the surface area \( S \) of the sphere The formula for the surface area \( S \) of a sphere is: \[ S = 4\pi r^2 \] ### Step 10: Differentiate the surface area with respect to time Differentiating with respect to \( t \): \[ \frac{dS}{dt} = 8\pi r \frac{dr}{dt} \] ### Step 11: Substitute known values into the differentiated surface area equation Substituting \( r = 6 \) and \( \frac{dr}{dt} = \frac{1}{36} \): \[ \frac{dS}{dt} = 8\pi (6) \left(\frac{1}{36}\right) \] This simplifies to: \[ \frac{dS}{dt} = 8\pi \cdot \frac{6}{36} = 8\pi \cdot \frac{1}{6} = \frac{4\pi}{3} \text{ cm}^2/\text{sec} \] ### Final Answers - The rate at which the radius is changing: \( \frac{dr}{dt} = \frac{1}{36} \) cm/sec - The rate at which the surface area is changing: \( \frac{dS}{dt} = \frac{4\pi}{3} \) cm²/sec
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