Concept of Weight and Mass

When you go with your parents to buy vegetables and fruits, did you observe how they buy vegetables?

Your parents ask the vendor for 1 kg of tomatoes, 2 kg potato, 1 kg cabbage, 1 kg brinjal, 2 kg mangoes…

What is 1 kg here? What is 2 kg? How do you know how much vegetables you get in 1 kg?

What is kg?

1 kg, 2 kg, 3 kg are the weights of the vegetables.

What is the weight?

Weight & Mass

Weight

The weight of an object tells us how heavy the object is.

A feather is not heavy because it has less weight. A bag of rice is very heavy because it has more weight.

When you try to lift your school bag, it is very hard to lift it sometimes because the bag is very heavy. That means the bag has more weight.

Activity

• Go around your house and try to lift anything, like a basket, the vegetables, an empty glass, a glass full of water. Try to identify the objects which have more weight and the objects which have less weight. Try to identify why the glass with water is heavier than the empty glass.

SURAJ AND THE MOON

It was the year 2086, all the humans on earth were going to live on Mars. The spaceship was ready to take everyone to the mars. The spaceship was very big. Everyone was going in it to mars, even Suraj was going to mars. He packed his bag. Suraj wanted to take his cricket bat that he got as a gift for his birthday but it was heavy but Suraj kept it in his bag. Everyone was ready and the spaceship started. The journey starts from the earth. The spaceship stops at the moon to fuel-up. And then it will go to mars.

When the spaceship stopped at the moon. Everyone got down the spaceship to eat something. Suraj and his friends wanted to play cricket on the moon so Suraj took his bag and came down from the spaceship. But the bag was not heavy this time. Suraj thought that someone took his bat from the bag. When he opened the bag the bat was inside. Suraj was shocked to see how the weight of the bag decreased.

• How do you think the weight of the bag was less on the moon and more on earth?

Mass

The weight of the bag was different on the moon and on earth. But the Mass of the bag was the same on earth and on the moon.

Weight of an object depends on the planet we are and its gravity. But the mass is the same everywhere.

Mass is the measure of how much matter is present in an object, more matter means more mass. Less matter means less mass 

The gravity of the moon is less than the earth’s gravity and that is why the weight of the bag is less than the weight of the same bag on earth.

The weight of every object depends on the gravity of the planet the object is but the mass of the object is always the same.

If your weight on earth is 32 kg then your weight on the moon will be 5 kg.

Trick question:

Your weight on earth is 32Kg and your weight on planet JUPITER is 80kg. Can you tell why weight on Jupiter is more?

Quiz

1 ) Mass is the measure of ______ present in an object

• Water
• Weight
• Mass
• Air

2 ) Weight depends on

• Mass
• Gravity
• Nothing
• Mass & gravity

3 ) The weight of an object is the same on earth and on the moon?

• True
• False

4 ) Mass of an object is the same on earth and on the moon?

• True
• False

5 ) The unit for weight is?

• Kg
• Litre
• Newton
• M/s