How Does a Thermos Keep Soup Warm?

What Crafty Clover says in this video

Intro

Hi there, curious minds! I'm Crafty Clover! Let's discover something amazing. How does a thermos keep soup warm?

The Big Idea

A thermos keeps soup hot for hours. It can also keep a cold drink cold. Let's see how it does that!

Two Walls

Step one: two walls. A thermos has two walls with almost no air between them, a gap called a vacuum. With no air, heat cannot move across by conduction or convection.

Shiny Walls

Step two: shiny walls. Shiny walls reflect heat rays back inside. A tight lid stops warm air from escaping.

Together

Step three: all together. Together, these tricks slow down heat loss. So hot drinks stay hot and cold drinks stay cold.

A Closer Look

Let's take a closer look! There are two walls. A vacuum sits between them. Shiny walls bounce heat back. A tight lid seals the top.

Quick Facts

Quick facts! The thermos was invented in the 1890s by a scientist named James Dewar. A vacuum gap stops heat from crossing. Shiny walls reflect heat back. Hot drinks stay hot, and cold drinks stay cold.

Think Like a Scientist

Now, think like a scientist! With a grown-up, fill a thermos with warm water. Fill a regular cup with the same warm water. Check each temperature after one hour. Which one stayed warmer? Then explain what you learned to a friend.

Outro

A thermos keeps drinks hot or cold by using a vacuum gap, shiny walls, and a tight lid. Next time you sip something warm, think about the vacuum hiding in the walls. Science is amazing! Keep wondering and keep exploring! Share what you learned with someone at home, and see what they think! Crafty Clover can be found on Amazon Books, Google Bookstore, and Apple Books. Available for purchase or download! Bye for now!