Question

The surface area of a sphere when its volume is increasing at the same rate as its radius is-

• A. 1
• B. $\frac{1}{2\sqrt{\pi}}$
• C. 4p
• D. $\frac{4\pi}{3}$

Answer 1

Answer: (A)

1

Answer 2

V = 4/3pr³ ̃ S = 4pr² ̃ dv/dt= dr/dt

̃ 4pr². dr/dt = dr/dt ̃ 4pr² = 1 ̃ S = 1