What weighs nothing( as in zero kilograms), but when you put one in a boat, the boat weighs less?

Question

What weighs nothing( as in zero kilograms), but when you put one in a boat, the boat weighs less?

Answer 1

everything has weight, even air.

Answer 2

A helium ballon placed in the cabin of a boat is the answer.

Answer 3

helium balloon

Answer 4

Nope, couldn't be a hole. It would be possible to knock a hole in the side of a boat without any loss of mass to the hull.  For instance, you have a steel barge, and run it into a bridge abutment. You might tear a hole in the steel, but no pieces are going to come off. Boat still weighs the same. In fact, it would start to weigh more as it takes on water.

Answer 5

The answer is "a hole".  Here's the difference between my answer an others.  I know why.  A hole doesn't have any weight (or mass).  When the boat sinks it will weigh less to an observer in the same medium.  It will still have the same MASS but it's weight on a scale at the bottom (while in the water) will be less than it's weight on a scale above the surface (while in the air).  It's all about buoyancy.

Answer 6

Hmm...a hole?