Thinking questions
If a metal block sinks in water, what does that tell you?
Its density is greater than water’s density
How do our shabbos candles show density?
Oil floats on top of water
What did the king want?
The tradesman to create a crown out of pure gold
DAILY DOUBLE!!!
Why couldn’t Archimedes melt the crown?
The king wanted the crown to stay intact.
DAILY DOUBLE!!! How could you compare densities of two odd-shaped objects?
Measure each object’s volume by water displacement, then divide mass by volume to compare densities.
If a liquid floats on another liquid, what does that show?
The floating liquid is less dense, and the lower liquid is more dense.
DAILY DOUBLE!!!
Why did the King think the tradesman cheated him?
Because he heard rumors that the tradesman mixed silver into the gold while keeping the same mass.
What happened when Archimedes got in the full bathtub?
Water spilled out as his body displaced it.
How did Archimedes know silver was mixed in?
He measured the crown’s volume and found it was too large for its mass to be pure gold.
DAILY DOUBLE!!!
Definition of density?
The amount of mass contained in a specific volume.
Which metal is more dense: gold or silver?
Gold is more dense.
Why did Archimedes shout “Eureka!”?
He realized how to measure the volume of an irregular object—by water displacement.
Why would a mixed-metal crown have a larger volume?
Because silver is less dense, so the same mass of mixed metal needs more space than pure gold.
Why does oil float on vinegar?
Oil is less dense than vinegar.
DAILY DOUBLE!!!
What did Archimedes realize in the bath?
The amount of spilled water equals the volume of the object submerged.
DAILY DOUBLE!!!
What property of gold and silver did Archimedes use?
Their densities—gold is almost twice as dense as silver.
Why do steel boats float if steal is heavy?
They are made hollow, so the combined density of steel + air is lower than water, allowing them to float.
Why is understanding density important? (Two examples)
1. Determining if the crown was pure gold
2. Explaining why liquids like oil and vinegar separate
3. Designing boats so they can float
What happens to crown size if more silver is added?
Its volume increases because silver is less dense
How did Archimedes figure out there was silver in it?
He measured the crown’s volume and found it was too large for its mass to be pure gold.