1. ## related rates problem

The volume of a sphere is increasing at a rate of 10 cm3/sec. Find the rate of change of its surface area when its volume is 32π/3 cm3.

Using my crazy logic I ended up coming up with 20 / r... anything will help

2. Originally Posted by jawisbest
The volume of a sphere is increasing at a rate of 10 cm3/sec. Find the rate of change of its surface area when its volume is 32π/3 cm3.

Using my crazy logic I ended up coming up with 20 / r... anything will help
Find the radius r when the sphere has a volume of 32pi/3. Next, V = (4pi/3)*r^3, so V' = 4pi*r^2*r' = 10. Use this and the value you found for r to find r'. Also, A = 4pi*r^2, so A' = 8pi*r*r'. Use the values you found for r and r' to find A'.

3. So did all of that and came up with 4.367... can anyone confirm this?

4. Originally Posted by jawisbest
So did all of that and came up with 4.367... can anyone confirm this?
$\displaystyle \frac{dS}{dt} \ne 4.367$

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### a sperical capsule is melted in water assuming that in the pricess of melting,the capsule remains sperical. it is given that the volume of the capsule is decreasing at the rate of 9(22/7) cm^3/sec. find the rate of change of its radius and surface area wh

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