Cool Floater, Hot Sinker

Cool Floater, Hot Sinker

Cool Floater, Hot Sinker
Reading Level

	edHelper's suggested reading level:	grades 5 to 7
	Flesch-Kincaid grade level:	6.87

Vocabulary

challenging words:

phenomenon, suspense, nitrogen, atmosphere, volume, helium, dioxide, questioning, carbon, pipes, substance, vapor, unit, heated, universe, therefore

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Cool Floater, Hot Sinker
By Trista L. Pollard

¹     It is the hottest day of the summer. You decide to celebrate your ability to survive the heat by drinking a tall, cold glass of lemonade. As you go to take your first gulp, you pause with a questioning look on your face. The little voice inside your head asks the question as the universe waits for the answer. "If ice is just frozen water, why does it float in liquid water?" Now, I am sure that if you were hot, you would have just continued to take your gulp of lemonade. However, I know this question has crossed your mind at some point. Well, I will not keep you in suspense any longer. This scientific phenomenon relates to a little word called density.

²     Density is the amount of something per unit of measure or weight of an object per unit of volume. Water is one of the few substances to have a different density as a solid (ice), as a liquid, and as a gas (water vapor). Water also has many unique properties especially when it is heated or cooled. Let's see what happens when water changes into its different forms.

³     Water has a definite volume which means that it takes up space in any container. It will take up the full amount of space regardless of the shape or size of the container. Water, like all objects (even you), has density. It is this density that determines if objects will float in liquids. Water changes to a solid or ice when it freezes at a temperature of 0 degrees Celsius. It changes into gas or water vapor when it boils at 100 degrees Celsius. There is a general rule for how matter or substances such as water will act when it gets hot or cold. When matter becomes hot, it expands, and when it becomes cold, it contracts. Water, however, is a very different type of matter.

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