# Thread: A circular pool of liquid (rate of change)

1. ## A circular pool of liquid (rate of change)

This one has my brain fried altogether.

A circular pool of liquid of constant depth 0.8cm forms under a leaky pipe. If the volume of liquid increases at a rate of 14cc/sec. Find the corresponding rate of change of the pool's radius at the moment in time when the total volume of spilt liquid is 92cc.

Any help would be great.

2. Originally Posted by manexa
This one has my brain fried altogether.

A circular pool of liquid of constant depth 0.8cm forms under a leaky pipe. If the volume of liquid increases at a rate of 14cc/sec. Find the corresponding rate of change of the pool's radius at the moment in time when the total volume of spilt liquid is 92cc.

Any help would be great.
shape of the pool is a right cylinder with constant height = 0.8 cm ...

$\displaystyle V = \pi r^2 h = \pi r^2 (0.8)$

take the time derivative of the above equation, sub in your given values, determine the value of $\displaystyle \frac{dr}{dt}$