Thermal Expansion - Why are gaps left between railway tracks? | #aumsum #kids #science

Summary

The script explains thermal expansion, a phenomenon where matter expands when heated. It illustrates this with examples like a thermometer's mercury rising in hot water and gasoline overflowing when heated. The script then relates this to railway tracks, explaining why gaps are left between rails to accommodate expansion and prevent accidents due to bending.

Takeaways

• 🔥 Thermal expansion is the phenomenon where matter expands when heated.
• 🌡️ A thermometer works by showing the rise in mercury level due to thermal expansion when placed in hot water.
• 💧 Mercury, being a liquid at room temperature, expands and causes the level to rise in a thermometer.
• 🚗 Gasoline expands when heated, which can cause it to overflow if not given space to expand, as seen in a filled gasoline tank.
• 🌞 Exposure to sunlight can heat gasoline in a tank, leading to expansion and potential overflow.
• 🛤️ Rails made of steel expand when heated, which can cause them to bend if not allowed to expand.
• 🔩 Railway tracks are made of steel rails that need space to expand to prevent bending and potential accidents.
• 🚉 Small gaps between rails are intentionally left to provide room for expansion and contraction of the steel rails.
• 🌡️ Thermal expansion not only occurs in summer but also due to friction between train wheels and rails.
• 🛑 Gaps between rails are crucial for preventing rail bending and ensuring the safety of train operations.

Q & A

What is thermal expansion?

Thermal expansion is the tendency of matter to expand when heated and contract when cooled. It occurs in solids, liquids, and gases.

Why does the level of mercury in a thermometer rise when it is placed in hot water?

The level of mercury in a thermometer rises when placed in hot water due to thermal expansion. The mercury expands as it heats up, causing the level to rise.

How does thermal expansion affect gasoline in a tank?

Gasoline expands when heated, which can cause it to overflow if the tank is filled to the brim with no space for expansion. This is why gasoline may come out of a hot, full tank.

Why do railway tracks have gaps between the rails?

Railway tracks have gaps between the rails to allow for thermal expansion. This prevents the rails from bending and causing accidents due to the expansion of steel when heated.

What happens to steel when it is heated?

When steel is heated, it expands due to thermal expansion. This property is utilized in various applications, including the design of railway tracks.

How do the gaps between rails prevent accidents on railway tracks?

The gaps between rails provide space for the rails to expand without bending. This prevents the train from derailing, thus avoiding accidents.

Can thermal expansion cause physical damage to objects?

Yes, if objects do not have space to accommodate thermal expansion, they can be damaged or deformed, such as rails bending if not designed with gaps.

Why is it important to understand thermal expansion in the context of thermometers?

Understanding thermal expansion is crucial for thermometers because it allows for accurate measurement of temperature changes by observing the expansion of the liquid inside.

What is the role of the small bulb in a thermometer?

The small bulb in a thermometer contains the liquid (like mercury) that expands when heated, which is then measured by the rise in the liquid level within the narrow tube.

How does the continuous friction between train wheels and rails contribute to thermal expansion?

The friction between train wheels and rails generates heat, which can cause the rails to expand. The gaps between the rails provide space for this expansion due to friction.

Are there any other materials besides steel that also expand when heated?

Yes, many materials expand when heated, including metals like aluminum and copper, as well as some plastics and liquids.