Class 5 EVS Chapter 7 NCERT Solutions: Energy—How Things Work

NCERT Solutions Class 5 Our Wondrous World Chapter 7 Energy—How Things Work (2025-26)

1. Observe and Write.

2. From your observation write down at least three things that you have noticed:

• Moving
• Providing light
• Making a sound
• Making things cool
• Making things hot

3. Activity 1: Extension Activity

Question: What would you change in the activity to make the toy move faster or slower?

Answer: To make the toy move faster, I can blow more air into the balloon before releasing. To make it move slower, I can fill it with less air or make the string surface rougher so there is more friction.

4. Activity 2: Rubber Band Guitar

Question: What happens if you use thinner or thicker rubber bands? Do they sound different?

Answer: Yes, thinner rubber bands produce higher-pitched sounds, while thicker bands produce lower-pitched sounds. The thickness and tightness of the band affect the sound produced.

5. Activity 3: Sun-powered Water Warmer

Question: What do you notice after keeping cups in sunlight and shade?

Answer: The water in the cup kept in the sunlight becomes warmer, showing that sunlight gives us heat energy. The water in the shade stays cooler.

6. Sources of Energy (Write)

Question: How is food cooked in your house?

Answer: In my house, food is cooked using cooking gas (LPG). Sometimes, we also use induction cooktops or electric ovens.

7. Discuss (Page 120)

1. What kind of fuel do you use at home for cooking?
2. What are the problems using too much wood or coal?

Answer:

• We mainly use LPG gas for cooking at home.
• Using too much wood or coal causes air pollution, health problems, and wastage of natural resources, and it can harm the environment.

8. Activity 4: Understanding How Fuel Works

1. Which diya burns longer? Why?
2. What is acting as a fuel here?

Answer:

• The diya with oil burns longer because oil acts as a fuel and provides more energy for burning.
• Oil is acting as a fuel in this activity.

9. Activity 5: Things That Run on Electricity

10. Generating Energy from Sun, Wind, and Water (Write)

Question: Can you think of more examples where we use the Sun, the wind or the flowing water?

Answer: We use the Sun to dry clothes and papads, wind to fly kites and move sailboats, and flowing water in watermills and for generating hydroelectricity.

11. Energy All Around Us (Table)

12. Let us reflect

1. What will happen if there is no electricity in your house for a day?
   Answer: If there is no electricity for a day, electrical devices will not work. There will be no lights, fans, TV, fridge or mixer. Daily activities and comfort will be affected.
2. Why is it better to use solar or wind energy instead of coal?
   Answer: Solar and wind energy are clean and renewable sources. They do not cause air pollution or harm the environment, unlike coal which produces smoke and harmful gases.
3. Give two examples where you have seen energy being stored.
   Answer: Energy is stored in batteries (like in torches or toys) and in our body when we eat food.
4. What is the one thing you can do at home to save energy?
   Answer: We can switch off fans and lights when not in use to save energy.
5. Find out how many kilometres a vehicle travels per litre of petrol or diesel. Ask about different vehicles. How will you compare them?
   Answer: A scooter travels about 40-70 km per litre, a car 10-20 km per litre, and a bus 3-6 km per litre. I will compare them by seeing which one goes more distance using one litre of fuel.
6. Look around your home or classroom. List any three objects that use energy and mention their source of energy. For example: Object; Fan → Energy Source: Electricity
   Answer:
   • Bulb → Electricity
   • Mixer → Electricity
   • Car → Petrol/Diesel
7. Create and share:
   (a) Draw or make a simple plan of a ‘clean energy home’ that uses solar, wind or any such source of energy.
   (b) Make ‘my energy diary’ for one day, record the number of times you have used the electricity fuel and so on.
   Answer:
   • I will make a plan with solar panels on the roof, using sunlight to power lights and fans in the house.
   • My energy diary: Today, I turned on the light 8 times, fan 5 times, and TV 2 times. I will try to reduce usage next time to save energy.

Understanding Energy—How Things Work in Our World

Mastering the concept of energy and its sources is essential for students in Class 5 EVS. This chapter explains how energy enables movement, heat, and light in our daily lives, helping students make real-life connections.

Exploring sun, wind, and water as clean sources of energy encourages sustainable habits. Learning about these energies supports students to make eco-friendly choices and boosts understanding for future science topics.

To score well in exams, regularly review each section on energy use and conservation. Practicing exercises boosts exam confidence and improves your ability to answer real-world application questions effectively.