Marshmallows making funny faces
With this experiment we’ll cause marshmallows to make funny faces and demonstrate a scien-terrific principle called pressure.
- Draw a face on both ends of a large marshmallow (the flat end). Draw ’em to look like Dad if possible – it’ll make the experiment much more humorous.
- Drop the marshmallow into a glass bottle. You’ll have to make sure and use a bottle that has a opening slightly larger than the marshmallow.
- Take the straw and wrap the clay about 1 inch from the end in such a manner that the clay forms a ‘ring’ around the straw. Place the short end of the straw into the bottle. The clay should stop the straw from dropping all the way into the bottle. Now press the clay around the mouth of the bottle so that the bottle is completely sealed and no air can get in (or out).
- Stand in front of a mirror so you can see the face on the marshmallow. Suck air out of the bottle. Make sure there are not leaks in the clay.
Yeah! Pretty funny huh? Now stop sucking on the straw. What happens to the marshmallow then?
Although a marshmallow appears to be solid it is actually filled with many pockets. These pockets are filled with air (much like a sponge). When you suck the air out of the bottle you are decreasing the pressure inside the bottle, which causes the spongy solid – the marshmallow – to expand. When you stop sucking on the straw and remove the straw from your mouth the air rushes back into the bottle, increasing the pressure and causing the marshmallow to return to its original size.
Pressure is often defined as force per unit area. In physics, the term is usually applied to fluids (gases or liquids). If a fluid is exposed to suitable forces, pressure is produced in it. The greater the force, the greater the pressure. Pressure is measured in pounds per square inch in the inch-pound system customarily used in the United States. It is measured in kilograms per square centimeter or pascals in the metric system.