science

chapter 8

Part A: True or False

A ___ cm³ piece of aluminum has a higher density than a _____ cm³

False (Density is a property of a material and does not change with size. A 1 cm³ and a 10 cm³ piece of aluminum have the same density.)

Corrected statement: A ___ cm³ piece of aluminum has the same density as a _____ cm³ piece of aluminum.

A hydrometer

Likely incomplete, but a hydrometer is used to measure the density of a liquid.

The buoyant force on an object

This statement is incomplete, but typically, buoyant force is equal to the weight of the fluid displaced by the object (Archimedes' Principle).

Part B: Matching (Buoyancy Types)

Positively buoyant → Floats in a fluid

Naturally buoyant → Stays suspended in a fluid

Negatively buoyant → Sinks in a fluid

Part C: Multiple Choice

A piece of aluminum, a piece of maple wood, and a piece of gold → Likely asking about density differences (gold is most dense, wood is least).

A scientist with a sample of a substance (volume & mass) → Use density formula: Density = mass/volume to identify the substance.

If a liquid has a density of ___ g/mL, the object that sinks in it must have a density greater than that.

Part D: Short Answer

Finding the density of an object (3 marks)

Measure mass using a scale.

Measure volume (for solids, use displacement method if irregularly shaped).

Calculate using Density = Mass / Volume.

Saltwater vs. Freshwater (4 marks)

Saltwater is denser than freshwater because of dissolved salt.

Objects that sink in freshwater may float in saltwater (e.g., the ocean effect).

Buoyant force is greater in saltwater.

Examples: Ships float better in saltwater than freshwater.