Kilogram
A kilogram is the standard unit of mass in the metric system, equal to 1,000 grams. It is the base unit for mass in the International System of Units (SI) and is used worldwide in science, commerce, and everyday life. Common conversions: 1 kg = 1,000 g, 1,000 kg = 1 metric ton. This Grade 7 math skill from Saxon Math, Course 2 builds metric system fluency for science courses, international contexts, and any application requiring mass measurement beyond the US customary ounces and pounds.
Key Concepts
Property The kilogram (kg) is the basic unit of mass in the metric system. $1000$ grams (g) $= 1$ kilogram (kg) and $1000$ milligrams (mg) $= 1$ gram (g).
Examples $\text{To get 1 gram of vitamin C, you need four 250 mg tablets, since } 4 \times 250 = 1000 \text{ mg}.$ $\text{A cat with a mass of 3.5 kg has a mass of } 3.5 \times 1000 = 3500 \text{ g}.$.
Explanation A kilogram feels like a big textbook and weighs about 2.2 pounds. For lighter things, like a paperclip, we use grams. For super tiny things like vitamins, we use milligrams. It's a simple system where everything is based on powers of 1000, making conversions a breeze!
Common Questions
What is a kilogram?
A kilogram (kg) is the basic metric unit of mass, equal to 1,000 grams. It is approximately 2.2 pounds in US customary units.
How do I convert between kilograms and grams?
Multiply kilograms by 1,000 to get grams. Divide grams by 1,000 to get kilograms. For example, 2.5 kg = 2,500 g, and 750 g = 0.75 kg.
What are common objects measured in kilograms?
A liter of water has a mass of about 1 kilogram. A typical textbook weighs about 0.5 to 1 kg. A newborn baby is about 3 to 4 kg. Body weight is measured in kilograms in most countries.
What is the difference between mass and weight?
Mass is the amount of matter in an object (measured in kilograms or grams) and does not change. Weight is the force of gravity on that mass (measured in newtons) and varies by location.
When do students learn about kilograms?
Kilograms are introduced in Grade 4-5 and reviewed in Grade 7. Saxon Math, Course 2 covers metric mass units in Chapter 8 as part of the metric system.
How does the kilogram fit into the metric system prefixes?
The prefix kilo- means 1,000. So 1 kilogram = 1,000 grams, 1 kilometer = 1,000 meters, 1 kiloliter = 1,000 liters. The kilo- prefix consistently means one thousand throughout the metric system.
How is the kilogram different from a pound?
A kilogram is approximately 2.2 pounds. The pound is a US customary unit. Most of the world uses kilograms for everyday mass measurements.