Hello all, I saw a picture today of a physics problem which is really a head scratcher in my opinion. See the attached photo. You have two columns of water on a scale. In the left column, you have a ping pong ball, attached by a string to the bottom of the container. In the right column, you have a metal ball fully submerged, but being held up by an external support.
Both containers have an equal mass of water, both balls have an equal volume, and the strings have no mass.
Which way will the scale move, and why?
The Attempt at a Solution
My gut instinct is to say that the scale will dip towards the right. But I don't know if this is mostly due to the buoyancy of the ping pong ball, the added weight of the metal ball, or some combination of roughly 50% of both.
As far as the ping pong ball is concerned:
I know that if you were to attach a helium balloon for example to the container, it will act to lift the container due to the buoyancy of helium in air. Likewise, a ping pong in water will have a buoyancy force which wants to lift the ball and pull the container up since its attached, but something about that scenario doesn't seem right, which is why I'm here. Thank you in advance!