@mandolino
if a snowball (sphere) melts so that its surface area decreases at a rate of 1cm^2/min, find the rate at which the diameter decreases when the diameter is 10cm?

sa=4pir^2 and i got -1/40pi cm/min for dr/dt is this right?

Question

@mandolino
if a snowball (sphere) melts so that its surface area decreases at a rate of 1cm^2/min, find the rate at which the diameter decreases when the diameter is 10cm?

sa=4pir^2 and i got -1/40pi cm/min for dr/dt is this right?

anonymous · Answer

give me a minute

anonymous · Answer

$$S=4\pi r^2$$ and 
$$D=\frac{r}{2}$$ so 
$$S=\pi D^2$$

anonymous · Answer

so i think you are off by a factor of 2.

anonymous · Answer

sorry, i misread the problem, and was taking long so sat answered it

anonymous · Answer

so its -1/20pi

anonymous · Answer

hmm thx just was unsure if i had to put the 1/2 in or i could just cut in half and just go wit that but now i understand