CBSE Class 5 EVS Energy How Things Work Worksheet Set 03

Fill in the Blanks

Question. Cars and scooters require __________ to keep running.
Answer: fuel (petrol or diesel)
Explanation: Vehicles have engines that burn fuel like petrol or diesel to get the energy needed to turn their wheels.

Question. In the diya experiment, __________ serves as the fuel to keep the wick burning.
Answer: Oil
Explanation: The cotton wick draws up the liquid oil, which burns steadily to keep the little flame glowing.

Question. __________ causes these things to move, shine, make a sound, or get warm and cold.
Answer: Energy
Explanation: Energy is the invisible power that makes everything happen, from lighting up a bulb to making your bicycle move.

True or False

Question. Electricity can merely produce light and cannot be used for motion or cooling.
Answer: False
Explanation: Electricity can do many different jobs! It spins the motor of a ceiling fan to create motion and powers a refrigerator to keep food cold.

Question. Thinner rubber bands vibrate more readily and produce a higher sound than thicker bands.
Answer: True
Explanation: Thin rubber bands shake back and forth very fast when plucked, making a sharp, high-pitched musical sound.

Question. Burning excessive wood or coal causes smoke and air pollution that harms our health.
Answer: True
Explanation: Smoky chulhas and coal fires release dark soot and toxic gases into the kitchen, which can hurt our eyes and lungs.

Questions / Short Question Answers

Question. Why does the diya with oil burn longer than the one lacking oil?
Answer: The diya with oil burns much longer because oil acts as a continuous fuel that feeds the flame. The diya without oil has only a dry cotton wick, which burns up and goes out in just a few seconds.
Explanation: Fire needs fuel to stay alive. The oil keeps feeding the flame slowly, whereas a dry wick burns out almost immediately.

Question. What would you alter in the activity to make the toy move faster or slower?
Answer: To make the balloon rocket move faster, use a bigger balloon filled with more air and a smooth, tight string. To make it move slower, use a smaller balloon with less air and a rougher or looser string.
Explanation: More air pushing out gives the balloon a stronger shove forward, while a smooth string reduces friction so the toy glides quickly.

Question. What are the hazards of using too much wood or coal?
Answer: Burning wood or coal creates thick smoke, black soot, and harmful gases that cause air pollution and can trigger breathing difficulties and coughs.
Explanation: When wood burns with lots of smoke, it fills the room with dirty air that is uncomfortable and unhealthy to breathe.

Question. What happens if you pluck thinner or thicker rubber bands? Do they sound different?
Answer: Yes, they sound different. Thinner rubber bands vibrate more rapidly and produce a higher-pitched sound, while thicker rubber bands vibrate more slowly and produce a deeper, lower sound.
Explanation: Just like the thin and thick strings on a real guitar, thinner bands make squeaky high notes and thick bands make deep bass notes.

Question. What are the devices in your home that need electricity to work?
Answer: Devices like light bulbs, ceiling fans, television, refrigerator, air conditioner, washing machine, and mixer grinder need electricity to work.
Explanation: These appliances are connected to wall sockets or batteries so electric current can flow in and power them.

Question. From your observations write down at least three things that you have noticed: Moving, Providing light, and Making things cool.
Answer:
• Moving: Pinwheels, water wheels, and electric fan blades.
• Providing light: The Sun, LED bulbs, and glowing diyas.
• Making things cool: A cool breeze, a refrigerator, and an air conditioner.
Explanation: We experience energy all around us every day—when the wind blows a pinwheel, when lamps light up our room, or when a fridge chills our water.

Question. How is food prepared in your house?
Answer: In most modern houses, food is cooked using cooking gas (LPG) on a gas stove or using an electric induction cooker. In some places, people also use firewood or coal.
Explanation: Cooking needs heat energy to boil water, cook vegetables, and bake rotis so they become soft and delicious to eat.

Match the Following

Question. Match each electrical appliance with its primary energy function:

Answer:
(i) Electric Fan — (c) Movement (mechanical energy) to blow air
(ii) Light Bulb — (d) Bright light energy
(iii) Television — (a) Light and sound energy
(iv) Refrigerator — (e) Cooling effect to keep food fresh
(v) Electric Iron — (b) Heat energy to remove wrinkles
Explanation: Electricity changes into different forms of energy depending on the machine: it spins the fan blades, warms the iron, lights the bulb, and cools the fridge.

Vocabulary Activity - "Guess the Word"

Question. Identify the invisible force that makes objects move, glow, create sound, or get warm.
Answer: Energy
Explanation: Energy cannot be seen directly, but we can see and feel what it does—like making a toy car move or a light bulb shine.

Question. Identify the liquid fuel traditionally poured into clay diyas to keep the wick burning.
Answer: Oil
Explanation: Vegetable or mustard oil provides the chemical fuel that keeps festive clay lamps burning brightly through the night.

Question. Name the household appliance that uses electricity to keep food chilled and fresh.
Answer: Refrigerator
Explanation: A refrigerator pumps heat out of its cabinet using electricity, creating a chilly environment that stops milk and vegetables from spoiling.