Related Rates: If a snowball melts so that its surface area decreases at a rate of 6 cm2/min, find the rate at which the diameter decreases when the diameter is 11 cm.

Answer 1

for a sphere,

a = πd^2
da/dt = 2π dd/dt
-6 = 2π*11 dd/dt

So, dd/dt = -3/(11π) cm/min