Buoyancy and radius of object

An iron ball is suspended by a thread of negligible mass from an upright cylinder that floats partially submerged in water. The cylinder has a height of 6.00 cm, a face area of 12.0 cm^2 on the top and bottom, and a density of 0.30 g/cm^3. 2.00 cm of its height is above the surface. What is the radius of the iron ball?

The ball is completely submerged but the cylinder is floating so which a should I solve it first, submerged or floating. I'm approaching it as a floating object right now.

Using the equation p(liq)gV(obj)= Mg

Is this in the right direction?
 

Doc Al

Mentor
44,642
966
I would treat each object separately, considering all the forces on them.
 

The Physics Forums Way

We Value Quality
• Topics based on mainstream science
• Proper English grammar and spelling
We Value Civility
• Positive and compassionate attitudes
• Patience while debating
We Value Productivity
• Disciplined to remain on-topic
• Recognition of own weaknesses
• Solo and co-op problem solving
Top