Paper Tea PotAmitabha Mukerjee
You are going by train and feeling thirsty. Grandma just scolded the kids for drinking from the bottle and making it jhootha but you can't find any glasses yourself . . . well – here is a nifty trick that will impress both kids and grandma!! Do it now by yourself, so you can unfold it on them later. . .
Let's start with a square of paper (go ahead, tear up this newspaper). Do you have some small kids around? Show them first how to make a square! Now, follow the figure and fold it. Don't fold it too hard at the middle of the diagonal (step 1) which becomes the bottom of the cup. Even if you have never done this sort of thing, this one is easy; just start it and the cup will be done!
Now, pour out your drink and enjoy it in peace. Can you re-use the cup? Experiment with different types of paper and see which ones can be reused . . .
Paper Tea Pot
Come to think of it, why wait for train travel? Now that summer is on its way, so is load-shedding. You find yourself sitting around in the flickering candle light . . . Ideal time to set free the kid inside you. So, gather around some real kids, and let's do some Storytelling Science.
Give everyone some paper (xerox paper works good). First, make the paper cup as above. Fill it about 2/3ds with water. Now, hold it on the flame of a candle. Yes -- let the flame lick the paper. Do you expect it to burn?
The paper won't burn so long as there is water on the inside. However If the paper is very thick or glossy, then the fire may cause the outside to become brittle and the fold at the bottom may open up, releasing the water inside and dousing the candle and making your wife (husband/ parents) unhappy.
Why doesn't the paper burn? Because the water inside can never get hotter than 100 degrees Centigrade. Now, paper does not conduct heat well, but if it is not too thick, the outside can never get to the 300 degrees needed to burn paper.
Can you make tea from it? Most often, the water will warm up but it may not reach boiling. You can get it to make some light tea liquor, not quite the gourmet stuff, but worth a try.
Why doesn't the water boil? Partly it is because water is one of the most difficult substances to heat up – it needs one calorie of heat for every degree for every gram. So if you have about 200 cc in there at 20 degrees C, then it will need 1600 calories of heat. Unlike a gas stove, a candle is designed to make light so it doesn't make a whole lot of heat; also, a lot of the heat goes outside as you will find out once your fingers start to burn . . .
In playing with kids, we feel younger ourselves, and renew our tryst with our beginnings. Studies have shown that people who play with children are less stressed, and have better indicators of cardiovascular health. Take the time, make this paper teapot, and share this storytelling science with some children. This column is not about science toys, it is really about releasing the child in us adults, so we can touch the lives of the burdened children all around us.
In the end, though, you must turn adult and tell the kids how dangerous fire can be. They must never ever try this unsupervised!
Amitabha Mukerjee (firstname.lastname@example.org) loves playing with fire when he is not teaching Computer Science at IIT