Breaking Board Paradox

Demonstration Kit

Introduction

Can a single sheet of paper hold a board that is struck with a hammer on the edge of a table? Demonstrate the tremendous force of air pressure.

Concepts

  • Air pressure
  • Surface area
  • Inertia

Materials

Hammer
Paper (20" x 30")
Soft pine board (1½" x ¼" x 24")

Safety Precautions

Wear protective goggles for this demonstration and have students (also wearing goggles) stand clear of the table during the demonstration. Students may want to strike a board without the paper on top. This is very dangerous and the fate of the flying stick very unpredictable.

Procedure

  1. Place a soft pine board on a sturdy lab bench or table. Allow the board to stick over the edge about 4–5 inches.
  2. Place one sheet of paper over the board and flush with the edge of the table. Flatten the paper smoothly on the tabletop and on the top of the board. Be sure the paper covers the entire board on the tabletop.
  3. Strike the part of the board that is protruding over the edge of the table with a quick, forceful blow from the hammer (see Figure 1).
    {12923_Procedure_Figure_1}
  4. The board should dramatically break at the edge of the table with the paper and the remainder of the board still lying flat on the table top.
  5. Calculate the surface area of the entire sheet of paper and determine the number of pounds of air pressure exerted on the surface of the paper. Any wonder the board broke?

Teacher Tips

  • Enough materials are provided in the kit to perform the demonstration 10 times—10 pine boards and 10 sheets of paper. Practice this demonstration several times before performing for students.
  • The keys to the demonstration are to push all the air out between the tabletop and the paper, and to strike the board hard, making good contact. Instead of hitting the board with the “hammer” end of the hammer, twist the hammer 90° and use the entire surface of the metal hammer body to strike the board. Grip the handle tightly when holding it this way. The larger surface area will provide a better chance to make solid contact with the board.
  • As a helpful hint, score the end of the board using a knife. This will help create a nice, even split. (Keep this little “trick” between you and the board.)

Correlation to Next Generation Science Standards (NGSS)†

Science & Engineering Practices

Using mathematics and computational thinking
Developing and using models
Asking questions and defining problems

Disciplinary Core Ideas

MS-PS2.A: Forces and Motion
MS-PS2.B: Types of Interactions
MS-PS3.A: Definitions of Energy
MS-PS3.B: Conservation of Energy and Energy Transfer
MS-PS3.C: Relationship between Energy and Forces
HS-PS2.A: Forces and Motion
HS-PS3.A: Definitions of Energy

Crosscutting Concepts

Cause and effect
Energy and matter
Stability and change
Systems and system models

Performance Expectations

MS-PS1-1: Develop models to describe the atomic composition of simple molecules and extended structures.
MS-PS1-2: Analyze and interpret data on the properties of substances before and after the substances interact to determine if a chemical reaction has occurred.
MS-PS3-2: Develop a model to describe that when the arrangement of objects interacting at a distance changes, different amounts of potential energy are stored in the system.
HS-PS2-1: Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration.

Recommended Products

Item No. Description
AP4713 Breaking Board Paradox—Demonstration Kit
AP4436 Hammer

†Next Generation Science Standards and NGSS are registered trademarks of Achieve. Neither Achieve nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.