Learning through Flashcards, Creativity & Academics

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 The Science Behind It  

When we sweat, our body is trying to cool down. But here’s what’s really happening:

• Sweat is made mostly of water.
• As it evaporates (turns into gas), it absorbs heat from your skin.
• This heat loss makes you feel cooler.
   

This is called evaporative cooling — a natural air-conditioner built into your body!

• Evaporation: Liquid turning into gas
• Latent Heat: The heat absorbed during a phase change (like water → vapor).
• Thermoregulation: Your body’s way of controlling temperature.
   

 Camels don’t sweat much — it helps them save water and survive in the desert!

 Use this as a cue card:

Q: Why does evaporation cause cooling?
A: Because it absorbs heat from the surroundings, lowering the temperature.
 

 The Science Behind It  

 It might seem strange, but ice floats in water because it’s less dense than liquid water.

Here’s what happens:

• As water freezes, it expands and forms a crystal structure.
• This structure takes up more space but contains the same mass.
• So, the density decreases — and anything less dense than water floats.
   

This is why icebergs float in oceans and why lakes freeze from the top down, not bottom up.

• Density: Mass per unit volume (how tightly packed matter is).
• Buoyancy: The upward force exerted by a fluid.
• Anomalous Expansion of Water: Water expands on freezing — unusual behavior compared to other substances.
   

 Water reaches its maximum density at 4°C — which is why aquatic life survives under frozen lakes.

• Drop an ice cube into a glass of water.
• Watch it float — but only about 9% of the ice stays above the surface!
• That’s because ice is roughly 9% less dense than water.
   

Q: Why does ice float on water?
A: Because ice is less dense than liquid water due to its expanded structure.
 

 The Science Behind It  

 The sky appears blue due to a phenomenon called Rayleigh Scattering.

Here’s how it works:

• Sunlight looks white but is made up of seven colors (like a rainbow).
• When sunlight enters Earth's atmosphere, it scatters in all directions.
• Blue light has a shorter wavelength, so it gets scattered the most.
• Our eyes pick up more of this scattered blue light, making the sky appear blue.
   

• Rayleigh Scattering: Scattering of light by particles smaller than its wavelength
• Wavelength: The distance between two peaks of a wave.
• Visible Spectrum: The range of light humans can see (VIBGYOR).
   

 At sunrise and sunset, the sky looks red/orange because the sunlight travels a longer path through the atmosphere, scattering away the blue and leaving behind the reds.

Use a glass of water and a flashlight to mimic the sun. Shine light through the side and observe how the color changes at different angles.

Q: Why is the sky blue?
A: Because blue light from the sun scatters more in the atmosphere.
 

 What’s Really Happening? 

Earth spins on its axis at about 1,670 km/h (1,038 mph) at the equator — but we don’t feel it at all.

Here’s why:

• We, the atmosphere, and everything on Earth are spinning together at the same speed.
• There’s no sudden movement or change in speed to notice.
• It feels like we’re standing still — just like sitting in a smooth-moving train.
   

• Inertia: The tendency of objects to stay in motion (or at rest) unless acted on by an external force.
• Relative Motion: Movement is observed only in relation to other things.
    

 The Earth’s spin helps create day and night.
One full spin = 24 hours = 1 Earth day.

  Stand in a spinning chair and hold a book.
Now, spin gently and try lifting the book.
You’ll feel stable because you're spinning along with everything — just like on Earth!

 Q: Why don’t we feel Earth spinning?
A: Because everything around us is moving with the Earth at the same constant speed.