Overview
This lecture explains the common metric units used to measure the mass of objects, clarifies the difference between mass and weight, and provides practical examples for grams, kilograms, and milligrams.
Mass vs. Weight
- Mass measures how much matter an object has, while weight is the force gravity exerts on that mass.
- In everyday language, mass and weight are often used interchangeably, though technically they are different.
Metric Units of Mass
- The gram (g) is the base metric unit for measuring small amounts of mass; examples: paper clip, stick of gum, or dollar bill each weigh about 1 gram.
- The kilogram (kg) equals 1,000 grams and is used for human-scale objects; for example, an average adult may weigh about 70 kg.
- 1 liter of water has a mass of 1 kilogram; a 2-liter bottle of water weighs 2 kilograms.
- The milligram (mg) is 1/1,000 of a gram and is used for measuring extremely small quantities, such as medication doses.
Key Terms & Definitions
- Mass — the amount of matter in an object.
- Weight — the gravitational force acting on an object's mass.
- Gram (g) — the base unit of mass in the metric system; about the mass of a paper clip.
- Kilogram (kg) — equal to 1,000 grams; often used for body weight or fluid quantities.
- Milligram (mg) — equal to 1/1,000 of a gram; used for precise, small measurements.
Action Items / Next Steps
- Review the definitions and examples for grams, kilograms, and milligrams.
- Be able to distinguish between mass and weight for upcoming lessons.