This chapter is about two important measurements: capacity (how much a container can hold) and weight (how heavy something is). We use these every day — filling a bottle with water, weighing fruits at the market, and more.
Capacity
- Capacity is the amount a container can hold when full.
- Standard units: millilitre (mL) and litre (L).
- 1000 mL = 1 L
- Small containers: mL (a teaspoon holds about 5 mL).
- Large containers: L (a water bottle holds about 1 L).
Comparing Capacity
We can compare by pouring one container into another, or by using measuring jugs marked in mL or L.
Weight (Mass)
- Weight tells us how heavy something is.
- Standard units: gram (g) and kilogram (kg).
- 1000 g = 1 kg
- Light objects: g (a pencil weighs about 5 g).
- Heavy objects: kg (a bag of rice weighs 5 kg).
Measuring Weight
We use a balance scale or a weighing machine.
A bucket holds 10 L. A mug holds 500 mL. How many mugs fill the bucket?
Step 1: Convert 10 L to mL: 10 x 1000 = 10000 mL.
Step 2: 10000 / 500 = 20 mugs.
Answer: 20 mugs fill the bucket.
Which holds more: a 2 L bottle or a 1500 mL bottle?
Step 1: Convert 2 L: 2 x 1000 = 2000 mL.
Step 2: Compare 2000 mL and 1500 mL.
Answer: The 2 L bottle holds more.
A bag of potatoes weighs 3 kg. A bag of onions weighs 2500 g. Which is heavier?
Step 1: Convert 3 kg to g: 3 x 1000 = 3000 g.
Step 2: Compare 3000 g and 2500 g.
Answer: The bag of potatoes is heavier.
A box weighs 4 kg 500 g. Write its weight in grams.
Step 1: 4 kg = 4000 g.
Step 2: 4000 + 500 = 4500 g.
Answer: 4500 g.
Rita fills a 5 L tank using a 250 mL cup. How many cups does she need?
Step 1: 5 L = 5000 mL.
Step 2: 5000 / 250 = 20 cups.
Answer: 20 cups.
Key Formulas
- 1 L = 1000 mL
- 1 kg = 1000 g
- Always convert to the same unit before comparing or calculating.
Common mistakes
Do not compare mL with L or g with kg directly. Always convert to the same unit first.
Summary
Capacity measures how much a container holds (mL, L). Weight measures how heavy something is (g, kg). Convert to the same unit before comparing.