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Practice each question, then open the answer or worked solution.
Have you seen someone blowing on their spectacles to wipe them clean? How does the air from the mouth help in cleaning the spectacles?
Answer: Yes, I have seen some people blowing air on to the spectacles to clean them. The moisture from the air blown gets converted into droplets of water on the glass and, hence, can clean the spectacles.
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: Yes, by blowing air into the glass, the moisture formed by the air blown comes in contact with the glass, which makes the glass look hazy. It’s not just the glass even the mirror also becomes hazy when air is blown onto it.
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: Yes, I can make the mirror hazy as well. When we blow the air, the moisture formed by the air blown comes in contact with the mirror, which makes the mirror look hazy. The air blowing from the mouth is wet.
Put your hand on your chest. When you breathe in, does your chest come out or go in?
Answer: By putting hands on the chest when we breathe in, the chest comes out.
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: The measurement of the chest when I took a deep breath in is 25cm.
The measurement of the chest when I breathe out is 21cm.
Yes, there was a difference between the two measurements; when we breathe in, the chest comes out and measures more. While we breathe out, the chest goes in and measures less.