(adsbygoogle = window.adsbygoogle || []).push({}); 1. The problem statement, all variables and given/known data

A glass ball of radius 2 cm sits at the bottom of a container of milk that has a density of 1.03 g/cm^3. THe normal force on the ball from the container's lower surface has a magnitude of 9.48 * 10^-2 N. What is the mass of the ball?

2. Relevant equations

Normal force + buoyant force = Weight

3. The attempt at a solution

My prof supplied the answer to this problem, so I know we're supposed to calculate the buoyant force (which I understand how to do) and add it to the normal force. What I don't understand is that when I first saw this question, I assumed the following: the milk and the atmosphere above the ball are all pushing down on the ball. The normal force therefore must contend with not only the weight of the ball but also the weight of the milk and air above. So I figured to answer the problem we'd have to take the normal force, add the buoyant force, then subtract the force from the milk and air above. However, the problem doesn't give you enough information to do that, since we don't know the height of the milk above the ball...so I assume my reasoning is wrong. Can someone explain why this problem is simpler than I initially thought?

Thanks!

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# Homework Help: Calculating weight of underwater object given normal force

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