Story by Ms. Rani Subramaniam

“Paati I am getting bored”, said Ram.

“I am also getting so bored”, said Shyam, his brother, who generally never agreed on what Ram said.

“Thatha please can we have ‘f ’ ”, said both in unison. Now ‘f ’ was the secret code between Thatha and the two brothers for phone.

If Thatha gave them the phone, they would watch videos, slouched. Thatha and Paati were the grandparents of the two boys who had their own favourite set of videos and never were they satisfied with the time given to them for watching videos. “Thatha , we have watched only for five minutes”, they would say after half an hour was over.

Once they started watching videos, even an earthquake would not shake them. The roof could collapse and fall, and they would still be glued to the video. Thieves could come into the house and they would not notice. The taps could be running and flooding the house, and even if they were in water they would not be aware. Such was the fixation to the phone.

Even when they got up in the morning and other children said their prayers, these two would ask for the phone.

Their mother had strict rules for watching videos on the phone. She allotted a specific time period per day for them to watch the videos.

Mother was right. Spending such a long time on the phone was bad for the eyes, ears, brain and posture. Some videos were bad too. Not good for children and taught them wrong things. She tried her best to explain all this to them, but the attraction to the phone was too strong. People who used cell phones on the roads caused a lot of accidents.

Paati said, “Come let us go out and play.”

“It is so sunny, we want to stay inside”, said the brothers.

Paati said that it was not that sunny. A little bit of playing in the sun would provide vitamin D for their bones. She said that they should call all their friends who stayed close by and play.

“What can we play Paati?” Paati said that she would think of all the games she played as a child. There were no cellphones or television or computers those days. Paati and her brother and sister did not have many toys to play with. But they had interesting times, playing games like:

 Seven tiles /Pitthu /Ezhu Kallu; Gilli Danda /Kitti Pul; Kaancha /Goli; Lattoo /Pambaram ; Skipping / kudhiattam; Chuppan Chuppai/ kannamuchi ; Dodge ball; Five stones; Palankuzhi; Carrom board; Hop Scotch /Paandi.

 Paati said she would think of more games that they played. These games did not cost money. They made children come together and become friends. The games were good exercise for the children. They got hungry. They ate well. And, playing outside also increased their immunity to diseases and gave them good air to breathe.

“Come, I will teach you all the games one by one.” Apart from a lot of fun there is a lot of science too in these games.

Today we will play seven tiles or ‘pithoo’, as they say in India.

For seven tiles or ‘pithoo’, we need an open ground, a tennis ball, and seven flat tiles.

Picking the right tiles from the outside is a lot of fun.

The game is played as follows: Children form two teams A and B. The seven tiles are stacked one on top of the other. From about a 15 m distance, a member of Team A tries to break the tower with a soft tennis ball. He is given only three tries. If he breaks the tower in three tries then his whole team tries to rebuild the tower. Meanwhile the members of the opposite team try to hit those who are building the tower. Each member who gets hit is out. If the person who has broken the tower gets hit, the whole team is out.

Once the tower gets rebuilt, team A shouts ‘pithoo’ and gets one point.

Now it is the turn of the other team. “Seems like fun Paati…let us play.”, said Ram and Shyam. They called some of their friends. They had a lot of fun, but they were playing on the road between two sets of houses, and they had to be careful that they did not break flower- pots and window- panes.

After they finished, they asked their Paati what science there was to the game.

Paati said that there was a lot of science to the game. Firstly, if the tiles are not stacked properly, they will topple. Without knowing any science, even a small child will stack the broader and thicker tiles at the bottom and gradually grade the tiles such that the smallest tile is on the top. This is because a bottom-heavy object is more stable than a top-heavy object.

Paati asked, “Do you feel scared about toppling over when you sit on a chair? I am sure you do not. But you do feel scared of toppling over, when you stand on that chair!”

“In many places there are double decker buses. The bus conductor does not allow standing passengers on the top deck,” said Paati.

“Why Paati?”, said the brothers. 

 “If there are standees on the top, then the bus becomes top-heavy and is unstable. There is a chance of the bus toppling over when the bus takes a turn or is on an incline.”, Paati explained.

“Can you explain Paati?”, said Ram.

“Well, let me explain in the simplest way,” said Paati.

 1. Every object has a weight because the earth pulls it towards itself. Weight of a body is the force with which the earth pulls the body.

2. We can think of the weight as acting at a single point on the object.  This point is called Centre of gravity of the body.

3. The weight of a body always acts vertically downwards (actually towards the Centre of the earth).

4. This weight can be represented by an arrow of a certain length.

5. If this arrow falls outside the base of the object when it tilts, then that object will topple.

6. If the arrow lies within the base of the object when the object tilts, the body will not topple.

 “Oh! so we should pile the tiles in a manner that the tower is bottom-heavy,” said Ram. “That is very clever of you, Ram”, said Paati. 

“Let us now think of some more science facts. When the player throws the ball, it actually follows a curved path because the earth is always pulling the ball down towards itself. We say that the ball has projectile motion. The player has to judge the angle and speed with which to throw the ball, so that the tower gets hit. You will learn more about this in the higher classes.”

“There are many examples of projectile motion. Look at these images and guess what they are.”

Paati was happy with the correct answers the boys gave. She now continued further. “The ball has energy because of its speed. The more the speed the more is its energy. This energy that the ball has, because of its speed, is called Kinetic Energy. The Kinetic energy of any object also depends on how massive it is. “Please explain this.”, said Ram. Paati thought for a while and said, “Let us suppose that the opposite team hits you with the ball. You will get hurt if the ball was thrown with a large speed.”

“Paati we have seen cricketers wear a protective helmet so that the fast ball does not hurt them.” Paati asked, “Do you know what would happen if the ball was made of iron?” The boys exclaimed, “Oh Paati, a ball of iron thrown with the same speed can kill too!” So, the Kinetic energy of the ball depends on both its mass and speed. “Phew that was a lot of science for one day. Thank you, Paati”, said Ram who was the elder of the two brothers.

Food for thought

1. Galileo, a scientist who lived in the 16th century, threw two balls of different masses from the top of the leaning tower of Pisa, at the same time. What was the result?

3. A satellite is just a projectile that is shot out from a height.