Here's my second attempt. My s is s = ((36pi)^(1/3))*V^(2/3). Taking the derivative of this would be {(2((36pi)^(1/3))*V^(-1/3))/3}*(dv/dt). And I think plugging in dv/dt would give me a solution but if that's the case, I don't know why my answer would differ.
Homework Statement
A spherical raindrop evaporates at a rate proportional to its surface area with (positive) constant of proportionality k; i.e. the rate of change of the volume exactly equals −k times the surface area. Write differential equations for each of the quantities below as a...