Marble Race--in Liquid!

A kitchen science project by Science Buddies

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Syrup or honey? Oil or water? Who will win in this liquid, marble-race challenge? Test the viscosity of common liquids around your house, and find out!

Key conceptsFrictionLiquids

Introduction

Background

There are several different ways scientists can measure the viscosity of a liquid. One method is called a "falling sphere viscometer," in which you drop a sphere (such as a marble) through a tube filled with liquid. By measuring how long it takes the marble to fall and how far it travels, you can figure out the liquid’s viscosity. You won't need to do any calculations in this activity—but you will get to "race" marbles by dropping them in different liquids. Will viscosity affect how fast the marbles fall? Try this project to find out!

Materials

• About a dozen equal-size marbles
• At least two equal-size tall, transparent drinking glasses (the taller the better)
• Assorted liquids from around your kitchen you have permission to use, such as water, syrup, honey, molasses, olive oil, vegetable oil, etcetera
• Strainer or colander
• A flat surface that can have liquids (water, oil, etcetera) spilled on it—or protection (such as a large trash bag) for the surface
• Optional: Extra bowls/containers and/or a funnel (for storing and reusing the liquids you use for the activity, if you do not want to throw them away)
• Optional: Volunteer to help you see which marble hits the bottom first

Preparation

• If you want to save and reuse the liquids you use from the activity, make sure you thoroughly wash your marbles and drinking glasses with soap and water, then dry them completely. This will assure they are clean and you do not get your liquids dirty.
• Prepare a work space on your flat surface and ensure that it is ready for any accidental spills (of water, oil, etcetera).

Procedure

• Fill your two (or more) drinking glasses with each of your different liquids to the same height. (To avoid spilling when you drop the marbles in do not fill them all the way to the brim.)
• Hold one marble in each hand, just above the surface of the liquid in each glass.
• Watch the glasses closely. Be prepared to watch the bottom to see which marble hits first. If you have a volunteer, have them look at the glasses, too.
• Let the marbles go at exactly the same time.
• Observe which marble hits the bottom of the glass first.
• Repeat the activity with a few more marbles to see if you get the same results. (Use clean, dry marbles each time.)
• If you have more than two different liquids, you can try racing marbles in other liquids to see what happens.
• Extra:
• Extra: Have an adult help you cool some syrup in the refrigerator and heat some on the stove or in the microwave.

Observations and results

You should have observed that the marbles fell more slowly through more viscous liquids (such as syrup) than through less viscous liquids (such as water). This is because the more viscous liquids have more resistance to flow, making it more difficult for the marble to travel through them. It might be hard to tell the difference between the results for some liquids, however—especially if your glasses are not very tall. This is why it is important to do multiple trials and have a volunteer help watch the marbles.

Cleanup

More to exploreRace Your Marbles to Discover a Liquid's Viscosity, from Science BuddiesWhat Is Viscosity?, from Princeton UniversityIt's a Solid… It's a Liquid… It's Oobleck!, from Science Activities for All Ages!, from Science Buddies

Science Buddies

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