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Stop Motion of Einstein

Evolving Education

Episode 03: Hot and Cold Water

Act 2 | Material Required | Einstein in his lab:

For this experiment, we need 5 things.

  1. A glass with Hot water
  2. A glass with Cold water
  3. Two food colours
  4. A plastic card
  5. 5. A tray

So let’s go!

Conducting the Experiment:

  1. Place the two identical glasses next to each other. One with hot water and the other with cold water.
  2. Add food colour, red to the hot water and green to cold. Let go!
    We will add food colour to both the glasses at the same time.
    Wait and observe carefully. Notice the colours mixing faster in the hot water . Oh Yes! This is happening because when we heat water its molecules spread farther than the cold water, giving more space for the colour to mix in.
  3. Grab the plastic sheet and place it on the top of the hot water glass just like this. Use your hand to turn the hot water glass upside down, remove your hand and watch the magic of air pressure.
  4. Place the upside down glass of hot water on top of the cold water glass
  5. Now, gently remove the card. Umm.. the liquids didn’t mix.
  6. Let's try to reverse the experiment with the cold one on top and the hot one at the bottom. We remove the card, gently and slowly and Voila! The liquids mix together

Scientific Principle and Application

Question: So, Why did the liquids mix when the hot water was at the bottom ?

This happened because hot water always wants to stay at the top so it rises up.

But wait a minute, Why does hot water rise ? Hot water rises when we heat it.

When we heat it, its tiny little particles also known as molecules begin spreading away And as they spread away they take up more space.

So, a volume of hot water weighs a little bit less than the same volume of cold water. Therefore, hot water is less dense than cold water.

Now you may ask hot water and cold water are just the same thing then why do they have different densities?

Remember friends a same substance can have different densities at different temperatures.

In fact our liquids mix and move together because they have different temperatures.

This up and down movement within any liquid or gas where the hot one goes up and the cool one comes down is called CONVECTION. Have you ever wondered why are smoke detectors always placed at the top?

Yes, you guessed it right. It’s because smoke is hot and hot air rises up From spring, summer, autumn to winter all these different seasons are due to convection. And Thanks to Convection, you and I can enjoy a steamy bowl of rice.

So, friends now that you know what convection is, let’s see how many examples can you gather on your own. Toodles!

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