Name: Derek Question: Hi Derek, If r is the radius of the sphere, V is its volume and S is its surface area, then V = 4/3pi r^{3} and S = 4 pi r^{2}. V, S and r are functions of time t. Since the volume of the balloon is decreasing at a rate proportional to its surface area, dV/dt = k S = k 4 pi r^{2} where k is a constant. Differentiate V implicitly with respect to t and simplify. Cheers, To return to the previous page use your browser's back button. |