If a snowball melts so that its surface area decreases at a rate of 2 cm2/min, find the rate at which the diameter decreases when the diameter is 9 cm.

Answer 1

Area=4PI(diameter/2)^2
dArea/dtime= 4PI*2 * diameter/2* ddiameter/dt*1/2 check that
dArea/dtime=2 PI diameter*ddiameter/dt
2=2PI*9*ddiameter/dt
solve