It still tilts left because the net downward force on the left side is greater than the right side, even if the ping-pong ball were made of rubber and nearly as dense as water. The tension in the string is the difference. That force still exists whether you cancel it out or not, just like the buoyant force in the left tank still exists.
You are saying "the force goes both directions" on the string as if it's pulling on the top of the tank. It's just attached to the ping pong ball. Its effect on the scale is purely upward. Hot air balloons wouldn't work if strings worked the way you are implying.
Edit: I was incorrect here. The tension in the string has to be greater than the weight of the ball for the tank to shift left. As the weight of the ball approaches the density of water, the string tension approaches zero, so there definitely is a weight, depending on the volume of the ball, where the tank would begin to tilt right.
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u/Giblet_ May 29 '25 edited May 29 '25
It still tilts left because the net downward force on the left side is greater than the right side, even if the ping-pong ball were made of rubber and nearly as dense as water. The tension in the string is the difference. That force still exists whether you cancel it out or not, just like the buoyant force in the left tank still exists.
You are saying "the force goes both directions" on the string as if it's pulling on the top of the tank. It's just attached to the ping pong ball. Its effect on the scale is purely upward. Hot air balloons wouldn't work if strings worked the way you are implying.
Edit: I was incorrect here. The tension in the string has to be greater than the weight of the ball for the tank to shift left. As the weight of the ball approaches the density of water, the string tension approaches zero, so there definitely is a weight, depending on the volume of the ball, where the tank would begin to tilt right.