Jumping Coin on a Bottle Trick

Jumping Coin on a Bottle is a super fun parent-child interactive stem activity. The coin will dance on the bottle mouth and sing. Crazy, right? The required materials are just a coin and a glass bottle which everyone probably has them at home. So, let’s get started with this amazing science project.

Age: 3+      Time: <2hours

 Safety 

Be careful with fragile glassware.

 Materials List 

• Glass bottle
• Coin
• Water
• Dropper

 Instruction 

Step 1/4 – Put an empty glass bottle in the freezer compartment for over an hour.

Step 2/4 – Place the coin in the mouth of the bottle and drip drops of water on the coin to seal the gap between the bottle and coin.

Step 3/4 – Warm the bottle with your hands. If the bottle is too freeze to hold, you can warm the bottle with some warm water.  

Step 4/4 – After a few minutes, the coin will jump up and down, giving off a sound similar to “hiccup”.

 Troubleshooting 

Why did my coin fail to jump?

- Make sure that the bottle has been put in the fridge long enough, the freezing time needs over one hour.

Check if the water completely seals the gap between the bottle and coin.

 Scientific Description 

The principle behind this Jumping Coin on a Bottle is the Thermal Expansion and Contraction of the air. The air inside the glass bottle is compressed in the freezer. The hand warms the air in the bottle causing the air to expand and increasing the pressure inside. When the pressure inside is higher than that of outside, the air inside pushes out, forcing the coin up. When the temperature of the air inside is the same as that of outside the coin will stop jumping. The daily used thermometer is made according to the principle of thermal expansion and contraction of liquid.

 Extensions 

Seal the gap with washing soap water and there can be some bubbles coming out of when then the coin is jumping. See if you can make it？