How do you keep a jar of water upside down?
Answers
Believe it or not, the secret to this science magic trick was in plain view of the audience the entire time. There’s simply a piece of mesh screen that is held in place by the lid of the jar. Unlike a normal jar lid, the Mason jar has a lid that comes in two pieces—the center section and an outer ring called the sealing band. You will only be using the outside ring portion of the lid for this science trick.
Place the plastic screen mesh over the opening of the jar and twist on the ring portion of the lid. Using scissors, cut around the lid to trim off the edges of the screen. If you want a more professional look, remove the lid before cutting the screen. You’ll see that the lid leaves an indentation in the screen material. Use scissors to cut around the indentation. What you’re left with is a screen insert that fits perfectly into the top of the sealing band. Place the screen over the opening of the jar and twist on the lid.
Your first inclination might be to try to hide the screen from your audience, but the truth of the matter is that no one will see it unless they know to be looking for it. Of course, you’ll need to have a little distance between you and your audience, but you can casually show the top of the jar in one hand while picking up the pitcher of water in the other and no one will suspect a thing. Go ahead, try it, and you’ll be amazed that you got away with flashing the secret right before their eyes! This is called “misdirection” and it fools the audience.
When you’re ready to perform the trick, fill the jar with water by simply pouring water through the screen.
Cover the opening with the index card. Hold the card in place as you turn the card and the jar upside down. Let go of the card. Surprisingly, the card remains attached to the lid of the upside-down jar. Carefully remove the card from the opening and the water mysteriously stays in the jar!
This is truly an amazing science magic trick because several scientific principles come into play to make the water appear to be suspended in the jar. Atmospheric pressure (the pressure exerted by the surrounding air) is the force that holds the index card in place. The card stays on the upside-down jar because the pressure of the air molecules pushing up on the card is greater than the weight of the water pushing down.
But how does the water stay in the jar when the card is removed? The answer is surface tension. The surface of a liquid behaves as if it has a thin membrane stretched over it. A force called cohesion, which is the attraction of similar molecules to each other, causes this effect. The water stays in the jar even though the card is removed because the molecules of water are joined together (through cohesion) to form a thin membrane between each tiny opening in the screen.
If you tip the jar at all, air will come into the jar and break the seal, causing the water to pour out. Tip the jar sideways and the water falls out of the jar. If you return the jar to its upright position, the air can no longer get into the jar and the rest of the water will stay inside. Now you have a special insight—be careful not to jiggle the jar or touch the screen because you’ll break the surface tension and surprise everyone with a gush of water. Okay, maybe that’s actually a good idea.
TAKE IT FURTHER
Answer:
keep a cardboard under the jar