Weight — Definition, Formula & Examples
Weight is a measure of how heavy something is. Common units of weight include ounces, pounds, grams, and kilograms.
Weight is a quantitative attribute of an object determined by comparing it to a standard unit of mass, such as the gram (g), kilogram (kg), ounce (oz), or pound (lb), using a scale or balance.
How It Works
You measure weight by placing an object on a scale and reading the number in the chosen unit. Lighter objects are often measured in ounces or grams, while heavier objects use pounds or kilograms. To convert between units, you use known relationships: 1 pound equals 16 ounces, and 1 kilogram equals 1,000 grams. When solving word problems, always check that the weights are in the same unit before you add, subtract, or compare them.
Worked Example
Problem: A bag of apples weighs 3 pounds and a bag of oranges weighs 40 ounces. Which bag is heavier?
Step 1: Convert the apples' weight to ounces so both bags use the same unit. There are 16 ounces in 1 pound.
Step 2: Compare the two weights in ounces.
Answer: The bag of apples (48 oz) is heavier than the bag of oranges (40 oz).
Why It Matters
Understanding weight is essential for everyday tasks like cooking, grocery shopping, and mailing packages. In science classes, you will measure weight and mass in experiments, and accurate measurement is the foundation of reliable results.
Common Mistakes
Mistake: Comparing weights that are in different units without converting first (e.g., saying 5 oz is more than 1 lb because 5 is greater than 1).
Correction: Always convert to the same unit before comparing. Since 1 lb = 16 oz, 1 pound is actually much heavier than 5 ounces.