NCERT Solutions for Chapter 15 Blow Hot, Blow Cold Class 5 EVS
Short Notes for Class 5 EVS Chapter 15 Blow Hot, Blow Cold
Blow Hot, Blow Cold is an informative chapter in which students will learn what happens when we blow hot or cool air. As well, the chapter explains how to blow cool and hot air. Students understand the concept better by using examples from real life. A real-time activity is used in this chapter to help students gain a clearer understanding of this phenomenon. Therefore, the blow hot, blow cold method will help clarify your understanding. In addition to cooling warm things, we blow warm things. Our breath contains water vapor that, when it comes in contact with a cold surface like a mirror, turns into tiny droplets of water
Chapter Name | The Super Senses NCERT Solutions |
Class | CBSE Class 5 |
Textbook Name | EVS |
Related Readings |
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Page No 141:
Question Do This:
Miya Balishtiye was confused when he saw the woodcutter blowing on his cold hands to make them warm and on the hot potatoes to cool them.
Question 1: Have you warmed your hands in winter by blowing on them when they are cold? How does it feel?
Answer:
My hands became warmer in winter when I blew on them. I feel warmer and more comfortable in it.
Question 2: Blow hard from your mouth onto your hands. How did you find the air from your mouth as compared to the air around? Was it hotter, or cooler?
Answer:
When I blew hard from my mouth onto my hands, the air was hotter than the air outside.
Question 3: Now put your hands at some distance from your mouth, and blow again. Does the air from your mouth feel warm? Why?
Answer:
Putting our hands close to our mouth and blowing air from our mouth, we feel that the air is not warm. As the hand is kept far from the mouth, the air blown from it becomes cold once it mixes with the surrounding air as it reaches the hand.
Page No 142:
Question Think and Tell:
Question 1: Can you think of any other way in which you use the warmth from your breath?
Answer:
By blowing warm breath on a handkerchief and keeping it over the redness of an eye, redness or injuries are relieved.
Question 2: Fold a piece of cloth 3-4 times. Now bring it close to your mouth and blow hard on it. Did the cloth become warm?
Answer:
Yes, the cloth became warm. This is because the air we exhale is warm.
Question 3: Balishtiye saw that the woodcutter was trying to cool the hot potatoes by blowing on them. What would have happened if he had eaten the potatoes without cooling them?
Answer:
His mouth would have got burnt from the hot potatoes if he had eaten the potatoes without cooling them. The air coming out of his mouth is colder as compared to the hot potatoes. So, he used air from his mouth to cool down the hot potatoes.
Question 4: Have you ever burnt your tongue when you ate or drank something that was too hot? How do you cool some food when it is too hot?
Answer:
We blow on some food to cool them or we leave them as it is uncovered to let them cool down in the surrounding atmosphere. We put some hot food in refrigerator also to cool them. Disclaimer: The first part of this question has to be answered by a student based upon his own experience. Considering this, the answer to the same has not been provided. The answer to the second part of the question is merely a sample. The students' answers can vary from this. Also the answer of two students can vary from each other.
Question 5: If you were to cool these three hot things - dal, roti, rice - in which ways would you do so?
Answer:
Dal and rice can be cooled by keeping them at room temperature or by keeping them in refrigerators. Also, we can use a spoon to cool them. For cooling roti, we can tear it a little and leave it for a minute. In this manner the heat gets released into the atmosphere and then we can eat it.
Question 6: Mini tried to cool her tea by blowing on it. Which do you think will be hotter - Mini's tea or the air she blew from her mouth?
Answer:
Answer:
The air from our mouths is used to clean spectacles, to whistle, to remove dust particles, to blow the flute, etc.
Page No 143:
Question Blow in Different Was:
Question 1: Make whistles of the things given below. Write in a sequence-from the loudest to the softest whistle.
- Wrapper of a toffee _________
- A leaf _________
- A balloon _________
- The cap of a pen _________
- Any other thing _________
Answer:
Here is a sequence of whistles from loudest to softest.
-There is a cap on the pen
-Put the mouth by putting your fingers in it
-Toffee can be wrapped in foil
-Through a balloon
-By way of a leaf
Question 2: Have you seen people playing different musical instruments like flute, dholak, been...., guitar, mridang, etc.? Can you recognise their sounds with your eyes closed? Find out more about these musical instruments. Collect their pictures too.
Answer:
My ears recognize the sounds of flutes, dholaks, bens, guitars, mridangs, and so on when I close my eyes.
A flute is one of the musical instruments we play with air. Thus, it belongs to the wind instrument family.
Guitar: A stringed instrument made up of strings.
Mridang: A mardang is a double-sided drum that is usually made using hollowed pieces of jackfruit wood. The instrument is a type of percussion.
Question Write:
Can you name some things which produce melodious or pleasing sounds when we blow into them?
Answer:
Flutes, Harmonica (mouth organ), bag pipes, whistles, been are some of the musical instruments that produce melodious or pleasing sounds when we blow into them.
Disclaimer: This is a sample answer. The answer of the students can vary from this. Also, the answers of two students can vary from each other.
Question Do this and discuss:
Question 1: Have you seen someone blowing on their spectacles to wipe them clean? How does there from the mouth help in cleaning the spectacles?
Answer:
Often people blow water onto spectacles in order to clean them. Water in the air is converted into droplets of water on the glass, which helps clean the spectacles.
Question 2: Take a glass. Bring it near your mouth and blow hard on it. Do this two or three times. Does the glass look hazy?
Answer:
The moisture formed when air blows into the glass causes the glass to appear hazy when it comes into contact with it. If air is blown onto a mirror, it also becomes hazy.
Question 3: Can you make a mirror hazy in the same way? Can you tell by touching the mirror what made it hazy? Is the air you blew from your mouth dry or wet?
Answer:
It is possible for me to make the mirror hazy as well. Whenever we blow air, moisture is formed by the air that is released, which comes into contact with the mirror and makes it look hazy. Wet air blows from the mouth.
Question 4: Put your hand on your chest. When you breathe in, does your chest come out or go in.
Answer:
When we breathe in, we exhale by putting our hands on our chests.
Question 5: Measure your chest
-Take a deep breath in
- Ask your friend to measure your chest with a thread.
Measurement ________
Now breathe out. Again ask your friend to measure your chest.
Measurement ________
-Was there any difference in the two measurements of your chest?
Answer:
My chest measures 27 cm when I take a deep breath.
When I breathe out, my chest is 23 cm.
The chest grew larger when we breathed in, so the two measurements differed. The chest measures less when we breathe out.
Page No 145:
Question How Many Breaths in:
Question 1: Put your finger under your nose. Can you feel any air when you breathe out from your nose?
Answer:
I can feel the air we breathe out when I put my finger under my nose.
Question 2: Count how many times in one minute do you breathe in and breathe out.
Answer:
My breathing rate is around 14-16 breaths per minute.
Question 3: Jump 30 times. Did you feel breathless?
Answer:
I felt breathless after jumping 30 times.
Question 4: Now again count how many times in one minute you breathed in and out.
Answer:
The number of breaths per minute I took after jumping was around 23.
Question 5: What was the difference in your count before and after jumping.
Answer:
A jump increases the rate of breathing by 7 counts, so the difference between the counts before and after jumping is 7 counts.
Page No 146:
Question What We Have Learnt:
Question 1:While playing, Amit hit a wall. His forehead was swollen. Didi immediately folded a scarf (4-5 times), blew on it and kept it on Amit's forehead. Why do you think didi did this?
Answer:
Didi blew warmer air from her mouth on the cloth to make the cloth warmer. This warm cloth reduces the swelling when put on the swollen portion of the head.
Question 2: We blow to cool hot things as well as to warm them. Give examples of each.
Answer:
Example of cooling things by blowing air: We blow air from our mouth to cool the food so that it can be eaten easily without burning our mouth. Example of warming things by blowing air: During winters we blow air from our mouth on our cool hands to warm them.
Disclaimer: This is a sample answer. The answer of the student may differ from this answer. Also the answer of one student may differ from the others. Students can answer this question based on their own experiences.