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## Main Question or Discussion Point

Hey everyone, this is my first post so I appreciate the replies.

Ok, like any good engineer shouldn't, I have no intention of violating the conservation of energy.

That being said, I need some help identifying where the violation occurs in the following mechanism I've been thinking about lately. (or does it?....)

Imagine a hollow metal sphere, say 10 kg, which has sufficient volume to make it positively buoyant.

It starts at the top of a vertical pipe and free-falls for say 10 m. At this point the mass has 1000 J of kinetic energy.

At this point, you harvest this energy as best you can (likely a mechanical wheel, or perhaps the sphere is magnetic and it passes an induction coil). If you can do this at even 50% efficiency, you just gained 500 J of energy.

After this, the sphere passes through a one-way valve via its own momentum into a vertical column of water, the water level being just slightly lower than the top of the air pipe. The vertical pipe and the column of water are connected at the top by a small ramp, and an actuator is used to push the sphere the final distance, say 1m, into the air pipe where the cycle starts again. Moving the 10 kg mass 1 m takes 100 J of energy, so thats subtracted from the 500 J gained to yield a positive 400 J.

So....isn't this performance over-unity? Of course, any work done on an object by gravity must be equal to the work done to get it up to that height in the first place, but in this case, isn't that being primarily taken care of by buoyancy?

Whats the issue here?

-Max

Ok, like any good engineer shouldn't, I have no intention of violating the conservation of energy.

That being said, I need some help identifying where the violation occurs in the following mechanism I've been thinking about lately. (or does it?....)

Imagine a hollow metal sphere, say 10 kg, which has sufficient volume to make it positively buoyant.

It starts at the top of a vertical pipe and free-falls for say 10 m. At this point the mass has 1000 J of kinetic energy.

At this point, you harvest this energy as best you can (likely a mechanical wheel, or perhaps the sphere is magnetic and it passes an induction coil). If you can do this at even 50% efficiency, you just gained 500 J of energy.

After this, the sphere passes through a one-way valve via its own momentum into a vertical column of water, the water level being just slightly lower than the top of the air pipe. The vertical pipe and the column of water are connected at the top by a small ramp, and an actuator is used to push the sphere the final distance, say 1m, into the air pipe where the cycle starts again. Moving the 10 kg mass 1 m takes 100 J of energy, so thats subtracted from the 500 J gained to yield a positive 400 J.

So....isn't this performance over-unity? Of course, any work done on an object by gravity must be equal to the work done to get it up to that height in the first place, but in this case, isn't that being primarily taken care of by buoyancy?

Whats the issue here?

-Max