Get free NCERT solutions for Class 5 EVS Chapter 15: Blow Hot, Blow Cold. Check the latest and detailed NCERT Solutions by subject experts. All these NCERT solutions will be quite helpful for easy understanding of various concepts explained in the NCERT Class 5 EVS Chapter 15. We have also assembled all the solutions in form of a PDF which students may download and keep with them to refer in offline mode as well.
NCERT Solutions for Class 5 EVS
Chapter 15: Blow Hot, Blow Cold!
NCERT Page No. 141
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.
(a) Have you warmed your hands in winter by blowing on them when they are cold? How does it feel?
(b) 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?
(c) Now put your hands at some distance from your mouth, and blow again. Does the air from your mouth feel warm? Why?
(a) Yes, I have warmed my hands in winter by blowing on them when they are cold. It feels warm and comfortable.
(b) The air from my mouth feels hotter as compared to the air around.
(c) When we put our hands at some distance from the mouth and blow on them, it does not feel much warm. This is because while travelling from mouth to our hands, the air from mouth gets mixed with the outside air and becomes cool.
NCERT Page No. 142
Think and Tell
(a) Can you think of any other way in which you use the warmth from your breath?
(b) 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?
(c) 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?
(d) 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?
(e) If you were to cool these three hot things – dal, roti, rice – in which ways would you do so?
(f) 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?
(g) Sonu was feeling very cold. He kept blowing on to his hands. Now think and write, which will be cooler – Sonu’s hands or his breath?
(h) For what other things do you blow air from your mouth?
(a) Yes, I can think of one more way in which we use the warmth from our breath. When someone gets redness in eyes or gets injured then warm air is blown on a part of hanky which is then softly pressed on eyes. This gives relief from the pain or discomfort. The same can be applied on a swollen forehead.
(b) Yes, the cloth became warm.
(c) His mouth would have got burnt due to the hot potatoes.
(d) Yes, I have burnt my tongue many times by sipping the hot tea. I cool the hot food items by blowing on them.
(e) Dal, roti and rice can be cooled by keeping them under fan for some time.
(f) Mini’s tea is hotter than the air she blew from her mouth.
(g) Sonu’s hands will be cooler than his breath.
(h) I blow air from your mouth for some other things like
- Cleaning my eye glasses
- Soothing my eyes when feels discomfort
- Removing dust from something
- For whistling
- To dry the painting colours on drawing sheet
NCERT Page No. 143
Blow in Different Ways
(a) 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 ______________
(b) 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.
(a) Sequence of whistles from the loudest to the softest:
– The cap of a pen
– Putting two fingers in mouth
– Wrapper of a toffee
– A balloon
– A leaf
(b) Yes, I have seen people playing different musical instruments like flute, dholak, etc., and I can recognise the sounds of most of these instruments with my eyes closed.
Some of the instruments are discussed below:
(i) Flute: It is a long hollow stick made of bamboo with holes in it. It is played by blowing air in it.
(ii) Dholak: It is a drum like structure made of wood and a leather membrane on its two ends. It is played by beating the leather membrane with hands or using two sticks.
(iii) Been: It is made from a dried bottle gourd. It is played by snake charmers by blowing air in it.
NCERT Page No. 144
Can you name some things which produce melodious or pleasing sounds when we blow into them.
Flute, whistle, mouth organ, bag pipe, etc., are some of the musical instruments which produce melodious or pleasing sounds when we blow into them.
Do this and discuss
(a) Have you seen someone blowing on their spectacles to wipe them clean? How does the air from the mouth help in cleaning the spectacles?
(b) Take a glass. Bring it near your mouth and blow hard on it. Do this two or three times. Does the glass look hazy?
(c) 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?
(d) Put your hand on your chest. When you breathe in, does your chest come out or go in.
(a) When we breathe out, we exhale carbon dioxide gas along with water vapour. The water vapour on colliding with the surface of the glass gets condensed due to which the glass becomes wet. This slightly wet glass can be easily cleaned with a soft cloth.
(b) Yes, the glass looks hazy after blowing on it for two to three times.
(c) Yes, I can make a mirror hazy in the same way. When we touch the mirror, we feel moisture on our fingers which shows that the moisture made the mirror hazy. This also shows that the air we blew from our mouth is wet.
(d) When I breathe in, my chest comes out.
NCERT Page No. 145
How Many Breaths in
(a) Put your finger under your nose. Can you feel any air when you breathe out from your nose?
(b) Count how many times in one minute do you breathe in and breathe out.
(c) Jump 30 times. Did you feel breathless?
(d) Now again count how many times in one minute you breathed in and out.
(e) What was the difference in your count before and after jumping.
(a) Yes, I can feel the air when I breathe out from my nose.
(b) I breathe in and out about 18 times in one minute.
(c) Yes, I felt breathless after jumping for 30 times.
(d) I breathed about 25 times in one minute after jumping.
(e) Difference in count of breaths before and after jumping was 7.
NCERT Page No. 146
What We Have Learnt
(a) 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?
(b) We blow to cool hot things as well as to warm them. Give examples of each.
(a) Didi blew on the scarf to make it warmer which. On pressing this warm cloth against the swollen part reduces the swelling and gives relief from pain.
(b) When we blow to cool hot things: We blow air from our mouth to cool hot food items, tea or milk.
When we blow to warm cool things: In winters, we blow air from our mouth on our cool hands to warm them.
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