Average density — Science definition
Total mass divided by the total volume enclosed by an object.
Where it is taught
- Density & Floating — Properties of Matter, Physical Science: Matter, Forces & Energy, Grade 8
In use
An object with average density below that of its surrounding fluid can float; one with greater average density tends to sink.
Density & Floating
Questions using average density
Problem 1
A hollow object has total mass 90 g and external volume 120 mL. Predict floating in water at 1 g/mL using its average density.
Hints
State what the supplied observations or conditions establish, and separate that from any assumption.
Answer and explanation
90/120=0.75 g/mL, below water's density. It can float under the model, provided it retains its enclosed air and does not take in water.