Strength in Numbers: Spaghetti Beams

A pasta science project from Science Buddies

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Will it bend or will it break? Learn how engineers study materials for use in the construction of bridges and buildings. Build your own bridge out of strands of pasta and see how strong it can be! 

Key conceptsMaterials scienceTension

Introduction

Background

In this project you will make a "beam" from bundled-together strands of spaghetti. As you hang weights from it, the beam will start to bend—putting some of the strands in tension and some in compression. Which ones break first depends on the physical properties of pasta. Do you think pasta will break first in tension or compression? Try this project to find out!

Materials

• Box of spaghetti
• Two objects of equal height, such as chairs, tables or large cardboard boxes
• Scissors (and adult's help when using them)
• String
• Paper clip
• Large plastic or paper cup
• Objects to use as weights (such as coins)
• Rubber bands or tape
• Recommended: safety goggles (to protect your eyes from flying fragments of broken spaghetti)

Preparation

• Set up two equal-height chairs, tables or cardboard boxes so they are next to one another, with a gap in between them that is just a few centimeters less than the length of a piece of spaghetti.
• Have an adult help to cut two small holes toward the top of your plastic or paper cup, just under the rim, on opposite sides from one another.
• Tie a loop of string through the two holes in your cup to form a "handle" (turning the cup into a mini-bucket).
• Bend a paper clip into either a "C"- or "S"-hook shape. This will allow you to hang the string handle from strands of spaghetti.

Procedure

• Place a single piece of spaghetti across the gap between your chairs (or tables, boxes, etcetera).
• Hang your cup from the strand of spaghetti using the paper clip hook that you made.
• start adding weight (such as coins) to the cup.
• Continue adding weight slowly. If you are using heavy items such as coins, support the cup with your hand when you drop in a coin, then gently lower the cup until the string pulls on the spaghetti. (Do not just drop or throw coins into the cup unsupported, as this could cause the spaghetti to break more easily.)
• Keep adding weight until the strand of spaghetti breaks. (If it bends and falls through the gap without breaking, move your chairs closer together and try again.)
• Now, bundle together five pieces of spaghetti. Do this by wrapping their ends in either rubber bands or tape to hold them together.
• Place the bundled strands of spaghetti across the gap and repeat the weight test. Remember to add weight slowly. Watch and listen to what happens as you add weight.
• Try the test again with a bundle of 10 strands of spaghetti (or more, if you have a large cup and lots of coins).
• Observe carefully where the strands that broke are located.
• Extra:
• Extra: Continue the test with larger bundles of spaghetti. You might need to use a larger container (such as a bucket instead of a plastic cup) to break the larger bundles. You can also perform this activity using water as a weight—just be sure the setup is located outside or where spills can easily be cleaned up.

Observations and results

More to exploreHow Bridges Work, from How Stuff WorksStrength in Numbers?, from Science BuddiesFeel the Forces of a Suspension Bridge, from Paper Bridges, from Popsicle Stick Trusses: What Shape Is Strongest?, from

Science Buddies

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