# Floating Objects and Weight

The Situation:

A ball is placed in a beaker filled with water and floats. It is also attached to the bottom of the beaker via a string.

The Question:

The ball is attached to the beaker, thus making the ball and beaker (and string included) a system. However, it is floating. Does the ball add to the weight of the beaker?

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It looks like putting a 1 kg hollow steel ball in a trough of water attached to a string and floats doesn't add weight to the trough when measured as a whole ;-) –  Waffle's Crazy Peanut May 1 '13 at 5:38

However, remember that the force exerted by the water on the object leads to an equal and opposite force exerted by the object on the water. Since at equilibrium, $m_{obj}g=\text{buoyant force}$, a force equal to the weight of the body is exerted on the water. When the beaker is weighed, this extra force is balanced by the normal force.