Questions: Density: How Tightly Packed Is It?

Question 1

A wooden block and a steel block are the same size. The steel block is much heavier. What does this tell you about their densities?

• A. They have the same density because they are the same size
• B. The wooden block is denser because wood is a natural material
• C. The steel block is denser — it has more mass packed into the same volume
• D. Density cannot be compared without knowing the color of each block

Answer: (C)

Density is mass divided by volume. Since both blocks have the same volume but the steel block has more mass, the steel block is denser. Its matter is packed more tightly. This is why equal-sized pieces of different materials can weigh very different amounts.

Question 2

A heavy object typically sinks in water.

• T. True
• F. False

Answer: False

False. Sinking depends on density, not weight alone. A large wooden log is heavy but floats because wood is less dense than water. A small steel marble is light but sinks because steel is denser than water. What matters is whether the object's density is greater or less than water's density.

Question 3

Why does a steel ship float even though steel sinks in water?

Model answer: A steel ship is hollow and filled with air, which gives it a very large volume compared to its mass. The overall density of the ship (steel plus the air inside) is less than the density of water, so it floats. A solid chunk of steel would sink because it is denser than water.

Density is mass divided by TOTAL volume. A ship is mostly air inside its steel shell. Even though the steel itself is dense, the enormous volume of air brings the average density of the whole ship below water's density. If the ship fills with water (loses that air space), it sinks — as the Titanic demonstrated.