Who Is Heavier? - CBSE Class 3 Maths NCERT Chapter 8

What Do 'Heavier' and 'Lighter' Mean?

In our daily lives, we lift many things. Some things are easy to lift, and we call them 'light'. Other things are difficult to lift, and we call them 'heavy'. 'Heavier' is just a way of comparing two objects. If you have a watermelon and an orange, the watermelon is heavier than the orange. The orange is lighter than the watermelon. But remember, the size of an object can sometimes be tricky! A big fluffy pillow might be much lighter than a small iron ball. This is because weight depends on what the object is made of, not just how big it looks. To be sure about which object is heavier without just guessing, we can use a balance scale. It's like a seesaw for objects! The side that goes down has the heavier object.

Measuring Weight: Grams (g) and Kilograms (kg)

Gram (g)

A gram is a unit used to measure the weight of very light objects. Think of a single paper clip, a feather, or a small eraser. These are all measured in grams.

Kilogram (kg)

A kilogram is a unit used to measure heavier objects. Your school bag, a big bag of rice, or even your own weight are measured in kilograms. A kilogram is much heavier than a gram.

The Magic Rule

This is very important! 1 kilogram is equal to 1000 grams. So, if you have something that weighs 1 kg, it's the same as having 1000 little things that each weigh 1 g. We write this as: 1 kg = 1000 g.

How to Use a Simple Balance Scale

1. Step 1: Get the Balance Ready — Imagine a simple balance scale with two empty pans, one on the left and one on the right. Before you start, the beam should be perfectly straight, meaning the pans are at the same level.
2. Step 2: Place the Objects — Carefully place the first object in the left pan. Then, place the second object you want to compare it with in the right pan.
3. Step 3: Watch the Pans — Observe what happens. The pan that goes down is holding the heavier object. The pan that goes up is holding the lighter object.
4. Step 4: Check for Equal Weight — If the pans don't move and the beam stays perfectly straight, it means both objects have the exact same weight. They are equally heavy!

Important Points to Remember

• A bigger object is not always a heavier object. A large balloon is lighter than a small cricket ball.
• Always pay attention to the units! 2 kilograms (kg) is much heavier than 2 grams (g).
• Remember the rule: 1 kg = 1000 g. This helps you compare weights. For example, 3 kg is heavier than 2500 g because 3 kg is equal to 3000 g.
• When adding or subtracting weights, make sure they are in the same unit. Either convert everything to grams (g) or everything to kilograms (kg).

Practice Questions with Solutions

• Q: A packet of chips weighs 50 g and a chocolate bar weighs 200 g. Which is heavier and by how much? A: Step 1: Compare the weights. The chip packet is 50 g and the chocolate is 200 g. Step 2: Since 200 is a bigger number than 50, the chocolate bar is heavier. Step 3: To find out 'by how much', we subtract the smaller weight from the bigger weight: 200 g - 50 g = 150 g. Final answer: The chocolate bar is heavier by 150 g.
• Q: Rohan bought 2 kg of potatoes and 500 g of tomatoes. What is the total weight of the vegetables he bought? (Give the answer in grams). A: Step 1: We need to add the weights, but they are in different units (kg and g). Let's convert everything to grams. Step 2: We know 1 kg = 1000 g. So, 2 kg of potatoes is 2 × 1000 g = 2000 g. Step 3: Now, add the weights in grams: 2000 g (potatoes) + 500 g (tomatoes) = 2500 g. Final answer: The total weight of the vegetables is 2500 g.
• Q: Which is heavier: a 4 kg watermelon or four 500 g packets of flour? A: Step 1: First, find the total weight of the flour packets. There are 4 packets, and each weighs 500 g. Total weight = 4 × 500 g = 2000 g. Step 2: Now, let's convert the watermelon's weight to grams so we can compare. 1 kg = 1000 g, so 4 kg = 4 × 1000 g = 4000 g. Step 3: Compare the weights: 4000 g (watermelon) and 2000 g (flour). 4000 is greater than 2000. Final answer: The 4 kg watermelon is heavier.
• Q: A jar full of jam weighs 1 kg 200 g. The empty jar weighs 300 g. How much does the jam inside the jar weigh? A: Step 1: We have the total weight (jar + jam) and the weight of the empty jar. To find the weight of the jam, we need to subtract. Step 2: Convert the total weight into a single unit (grams). 1 kg 200 g = 1000 g + 200 g = 1200 g. Step 3: Subtract the weight of the empty jar from the total weight: 1200 g - 300 g = 900 g. Final answer: The jam inside the jar weighs 900 g.

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