Tablecloth Trick – SICK Science
Yanking a tablecloth out from under food and dishes is easy… if you listen to Sir Isaac Newton.
We’ve all seen it done in the movies and figured there were camera tricks or edited film involved (there were probably some of both, too). If you have the right materials and a little practice, however, you can do it for real. The idea is really quite simple: yank a tablecloth out from under a beautiful place setting without destroying the meal or the dishes. It’s another way to thank Sir Isaac for cluing us in on the Laws of Motion.
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- Tablecloth (no hems on the edges)
- Smooth, flat tabletop (preferably with a straight edge)
- Unbreakable dinner plates, saucers, and glasses with smooth bottom surfaces (the heavier, the better)
- Adult supervision
- Get everything you need, and more table tricks, with the "After Dinner Science" kit.
Check the tablecloth you want to use and make sure there are no hems on the edges. A hem means the edge of a piece of cloth has been turned under itself a number of times and sewn. It prevents frayed edges,
Spread the tablecloth onto the tabletop with about 2 feet (61 cm) of the tablecloth on the table. The rest can hang down over the edge for now. Make sure there are no wrinkles or humps in the cloth.
You’ll want to practice several times. Pull the cloth as fast as you can straight down along the edge of the table.
Place the practice cups, plates, and utensils on the tablecloth close to the edge of the cloth on the table (for practice). This makes for less tablecloth to pull out from under the stuff sitting on it. It builds your confidence.
Grab the hanging end of the tablecloth with both hands so they’re lower than the surface of the table Yank the tablecloth out from under the dishes by pulling it downward very quickly at the edge of the table. Keep your hands below the table top. Practice this several times.
The key is the quick, downward motion. Tell yourself, “Pull down… not out.” Also, keep the cloth parallel to the edge of the table top so it comes off all at once along the edge.
How Does It Work
The only way to make this work is to just do it. If you’re nervous, start with only a dinner plate and do it over a carpeted floor. You’ll be amazed when it works and you’ll add a saucer, then a cup, and so on. Be sure to thank Sir Isaac Newton for his help in making you an overnight success. Plain and simple, the Tablecloth Trick works because of inertia. In his First Law of Motion (there are three), Newton described inertia as the tendency of an object at rest to remain at rest unless a force acts upon the object to move it. Inertia for an object in motion is the tendency for that object to remain in motion, unless a force acts on it to speed it up, slow it down, stop it, or change its direction. In terms of the Tablecloth Trick, inertia is the key. The inertia of the stuff on the table keeps them where they are despite the speeding tablecloth underneath them.
There is, however, another component to consider: friction. As explained, all of the objects (the plate, bowl, cup, utensils, etc.) are at rest. When you pull the cloth, friction between the cloth and the bottoms of the dishes acts on the them for a short time in the direction of the pull. Except, the tablecloth is “slippery,” so the force of friction is small and the cloth slides out from underneath the objects without dragging them too much. It helps to have a very smooth tabletop, as well. A towel or blanket would bring a lot of friction to the party and would be a poor choice as a tablecloth for this activity.
Take It Further
Instead of testing different plates, bowls, and glasses, test different masses on the plates. Make a plate or bowl heavier by adding something with some weight like a can of beans. How does adding weight (mass) change the way the tablecloth moves out from under the dishes? You might be surprised.