======Air Pressure Breaks a Ruler====== **Materials: **{{$demo.materials_description}}\\ **Difficulty: **{{$demo.difficulty_description}}\\ **Safety: **{{$demo.safety_description}}\\ \\ **Categories:** {{$demo.categories}} \\ **Alternative titles:** The Heavy Newspaper ====Summary==== {{$demo.summary}} ====Procedure==== - Place a wooden ruler so that about 5 inches extend beyond the edge of a sturdy table. - Strike the overhanging end sharply with the side of your hand and observe the result. - Reset the ruler in the same position on the table. - Spread a sheet of paper flat across the portion of the ruler on the table, smoothing out air pockets. - Strike the overhanging end of the ruler in the same way as before. - Observe that the ruler is much harder to move and may snap from the force of your strike. ====Links==== Air Pressure Breaks a Ruler - George Mehler: {{youtube>UvMmfacVA24?}}\\ 📄 Break a Ruler Using Newspaper and Atmospheric Pressure - Education.com: [[https://www.education.com/activity/article/pressure-news-pretty-heavy/]]\\ ====Variations==== * Try using different sizes of newspaper sheets to see how surface area affects the result. * Try gently lifting the ruler with the paper covering it - notice the suction effect. ====Safety Precautions==== * Strike with the soft part of your hand to avoid injury. * Use only thin, inexpensive wooden rulers (not metal-edged rulers, which may cause injury). * Clear the area of breakable objects, as rulers may snap and fly off the table. * Adult supervision recommended for children performing this demonstration. ====Questions to Consider==== * Why is it harder to break the ruler when covered with newspaper? * How does atmospheric pressure contribute to the effect? * Why is smoothing the newspaper important? * How does this relate to the concept of suction cups? * How much force do you think the atmosphere exerts per square inch on the paper?