Power of the straw (Michael Flores)

Author

Michael Flores

Principle(s) Illustrated

Air pressure

Force distribution

Mass of Air

Standards

Stability and Change

Much of science deals with constructing explanations of how things change and how they remain stable.

In many situations, a dynamic and condition-dependent balance between a reaction and the reverse reaction determines the numbers of all types of molecules present.

Questioning Script

Prior knowledge & experience:

Straws are bendable

Potatoes have a hard surface

Root question:

How does something so flimsy, puncture a hard surface like a potato

Target response:

The real secret is inside the straw—it’s air. Placing your thumb over the end of the straw traps the air inside. When you trap the air inside the straw, the air molecules compress and give the straw strength, which in turn keeps the sides from bending as you jam the straw through the potato. The trapped, compressed air makes the straw strong enough to cut through the skin, pass through the potato, and exit out the other side. Without your thumb covering the hole, the air is simply pushed out of the straw and the straw crumples and breaks as it hits the hard potato surface.

Common Misconceptions:

Hard materials are impenetrable

Photographs and Movies

Applications to everyday live

Compressed air allows for extreme pressure to be expelled quickly like in fire extinguishers.

Air brakes

Power tools

References

Steve Spangler science (Straw through Potato)