To determine which object weighs the most, you need to understand the concept of weight and how it differs from mass.
Key Concept:
- Weight = Mass × Acceleration due to gravity (g)
- On Earth, g ≈ 9.8 m/s²
This means that if objects are at the same location (like Earth), the object with the greater mass will weigh more.
Conceptual Understanding:
If different objects are given (such as iron, cotton, stone, etc.), then:
- Always compare their mass, not just their size.
- A larger-looking object (like cotton) may weigh less because it has low density.
- A smaller but denser object (like iron) may weigh more.
Example:
- 1 kg of iron vs 1 kg of cotton → Both weigh the same because mass is equal.
- 1 m³ of iron vs 1 m³ of cotton → Iron weighs more because it has higher density.
Important Insight:
- Weight depends on mass, not just size or volume.
- Density matters when volume is the same.
Exam Tip:
Always check:
- Whether mass is the same or volume is the same
- Whether gravity is constant (usually assumed on Earth)