Water drains from a tank. Write a differential equation.

[cp255]

2. Water drains out of an inverted conical tank at a rate proportional to the depth y of water in the tank. Write a differential equation for y as a function of time.

My answer was dy/dt = ky.

This was from a weekly homework set where there were only 5 problems. I feel like I am missing something since my answer is too simple and it didn't take very much work. Am I missing something?

 

[Dick]

2. Water drains out of an inverted conical tank at a rate proportional to the depth y of water in the tank. Write a differential equation for y as a function of time.

My answer was dy/dt = ky.

This was from a weekly homework set where there were only 5 problems. I feel like I am missing something since my answer is too simple and it didn't take very much work. Am I missing something?

Yes, that's too simple. The rate at which the water drains is related to the rate of change of the volume of the tank.