# Ice Diamond Riddle SOLUTION ft. Vsauce's Michael Stevens | Summary and Q&A

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July 6, 2018
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Physics Girl
Ice Diamond Riddle SOLUTION ft. Vsauce's Michael Stevens

## TL;DR

When an ice cube with a diamond inside is dropped into a glass of water, the water level goes down because the diamond displaces less water than the ice cube.

## Key Insights

• π¦ The buoyant force on an object floating in water is equal to the weight of the water displaced by the object.
• π§ The ice cube floats because it displaces its own weight in water, not just the volume.
• π§ When the ice cube melts, the diamond inside sinks and displaces its volume, causing the water level to go down.
• π«  The density of ice varies from most solids, as it becomes more dense when it melts.
• β Understanding Archimedes' principle is crucial to solving this riddle.
• π§ The water level would still go down if there was no diamond inside the ice cube because the water in the ice cube is added to the glass.
• π¦ The depth to which an object is submerged in water depends on the weight of the water it displaces.

## Transcript

Thanks to Curiosity Stream for supporting PBS Digital Studios. Hey, I'm Dianna. You're watching Physics Girl, Riddle Series. Here's where we left off in the last video. Michael Stevens, from V Sauce, is in the hot seat answering a buoyancy riddle, which I know that you already attempted to answer in the comments of the last video. I laid out the p... Read More

### Q: Why does the ice cube float in water?

The ice cube floats because it displaces its own weight in water, according to Archimedes' principle. This buoyant force keeps it buoyant above the water.

### Q: Why does the water level go down when the ice cube melts and the diamond sinks?

When the ice cube melts, the diamond inside sinks and displaces only its volume in water, which is less than the volume of the ice cube. This causes the water level to go down.

### Q: What determines how deeply an object will be submerged in water?

The depth to which an object is submerged in water is determined by the weight of the water it displaces. If an object's weight is equal to or less than the weight of the water it displaces, it will float.

### Q: Is the water level affected if there is no diamond inside the ice cube?

If there is no diamond inside the ice cube, the water level would still go down when the ice cube melts because the water in the ice cube is added to the glass, displacing less water.

## Summary & Key Takeaways

• In a riddle, the question is posed: When an ice cube with a diamond inside is dropped into water, does the water level go up, down, or stay the same?

• The ice cube floats because it displaces its own weight in water, but when it melts, the diamond inside sinks and displaces its volume, causing the water level to go down.

• Archimedes' principle explains that the buoyant force on an object floating in water is equal to the weight of the water displaced by the object.