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प्रश्न
Have you seen someone blowing on their spectacles to wipe them clean? How does the air from the mouth help in cleaning the spectacles?
उत्तर
The air blown from the mouth is hot and the glass of the spectacles is comparatively colder. The hot air we breathe out contains water vapours which turn into tiny droplets of water when it comes in contact with the colder glass. This makes the glass moist and hazy.
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संबंधित प्रश्न
If you were to cool these three hot things – dal, roti, rice – in which ways would you do so?
For what other things do you blow air from your mouth?
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
Have you seen people playing different musical instruments like flute, dholak, been ...., guitar, mridang, etc. Can you recognize their sounds with your eyes closed? Find out more about these musical instruments. Collect their pictures too.
Now again count how many times in one minute you breathed in and out.
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?
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?
You have all heard the ‘tick tick’ of the clock. Have you seen a doctor using a stethoscope to listen to our chest? What do you think she hears? Where is the sound coming from? Is there a clock inside your chest that keeps ticking away?
Do you want to listen to your heartbeat? Take a rubber tube as long as the distance from your shoulder to your elbow. At one end of the tube fix a funnel. Place the funnel on the left side of your chest. Put the other end of the tube to your ear. Listen carefully. Did you hear a dhak dhak sound?
Can you understand from the movement of the snake - if the air is moving upwards or downwards?
