## The Space Elevator

#### Topic: Fractions, Decimals And Percentages On A Number Line

“This is the worst data I have ever seen. If this continues, there will be no water left on earth. Life on earth is in danger. We need to do something”, says Uncle Math. “I am shocked too. The rate at which the water is reducing on earth, is definitely a cause of concern”, says Uncle Science.

Due to the misuse of water in the past by humans, there is an extremely small amount of drinkable water left in the natural bodies that can be used for sustaining life on earth. What will Uncle Science and Uncle Math do now?

“We should launch a water search operation on various planets before things go out of hand”, suggest Uncle Science. Uncle Math agrees and together they plan on how can they execute this search operation.

“Alright! To make this search operation budget-friendly and fast, we will use the space elevator that I had designed years ago”, suggests Uncle Science. “What is a space elevator?” asks Triho. “Space elevator is a special kind of elevator that will take us up into the space”, explains Uncle Math.

Triho is amazed. “I thought the elevators can be used only to travel from one floor of a building to another”, he says. All three of them board the space elevator to start the operation.

“So where are we going first?” asks Triho. “As per my research, there are some traces of water on the planet Mobo. So we are going there first”, says Uncle Science. He enters the destination and the distance meter shows 1 astronomical unit (au).

Thud! The space elevator starts. Uncle Math, Uncle Science and Triho are excited yet nervous. This mission’s success is important to save the planet.

As the journey begins, the distance meter displays the live path. “Oh wow! The map looks interesting. Is it showing the distance we have covered? asks Triho. “Yes, dear. The map is also showing us how much of the journey is left too”, explains Uncle Science.

“But how? And what are these numbers indicating?” questions curious Triho. “Observe the map and the route carefully. What do you see?” asks Uncle Math. “ Oh yes! The route resembles a number line. A number line that is divided into 10 equal parts. The line begins at 0 and ends at 1. The smaller parts in between are labelled 1/10, 2/10, 3/10 so on upto 1”, he answers.

“So smart! You are absolutely right. What else do you notice?” questions Uncle Math. “I notice that 1/10 is also labelled as 0.1 and 10%. Similarly, 2/10 is 0.2 and 20%. Why different representations? Is there a connection between these?” he asks.

“Yes, there is. When I divide 1/10, I get 0.1 as the answer. 0.1 further converted to percentages gives 10% as the answer. Percentages are well suited to indicate how much of the journey is completed. Right now we are at 1/10, which means we have completed 10% of the journey only yet. Still, there is a long way to go”, explains Uncle Math.

Triho is astonished. He decides to observe the route even more closely now. “Look! We have reached 2/10. That means 20% of the journey is completed. Correct?” he says. Uncle Science and Uncle math agree with him.

Soon they reach 5/10 points on the route. Can you guess how much of the journey have they completed now?

Yes, 50% of the journey is already completed. Uncle Science seems worried, hoping for his research to be true.

60%, 80% and 90%, soon they cross these points. Can you write the decimal and fraction representations of these on the number line?

“90% journey competed. That means we are very close to planet Mobo. Wohoo!” says excited Triho. Uncle Math and Uncle Science are apprehensive yet optimistic about it.

“Destination arrived!” announces the distance meter. Can you guess how much of the journey have they completed?

100%! Absolutely right! Since 10 out of 10 parts are covered, the entire journey is covered which means 100%. Triho, Uncle Math and Uncle Science are all ready to walk out of the elevator. Will they really find water on planet Mobo?

As they land on planet Mobo, Uncle Science spots some huge stone-like objects. The land is dry and there is no trace of water yet. “This is bad! Can’t believe this. How did my research get wrong?” says disappointed Uncle Science. Is there no water here really?

“No! Uncle Science. Your research is not wrong. Look there, I can spot a small tree. Doesn’t that indicate the presence of life? Life cannot exist without water. That means there is water here. Let us rush there and find out,” says Uncle Math. Hearing this Uncle Science is elated. All of them are hopeful.

They run quickly to get close to the tree. Will they find water here?

“Oh my goodness! I can’t believe my eyes!” says Uncle Science. “So much water! So many trees! Hurrah! We will be able to save our planet now”, says Triho. As they get close to the tree, they find a huge water reservoir, surrounded by more and more trees. They jump out of joy.

“We will save our planet! We did it,” says Uncle Math. They hug each other, sing and dance to celebrate this moment.

<After some years>

Uncle Science and Uncle Math are at peace now. Their planet is back to normal. Everybody is living happily. “The data indicate a sufficient amount of water to sustain now,” says Uncle Science. Triho is extremely proud of his teachers. It has been a long yet peaceful journey towards sustainability.

## We Learnt That…

• A space elevator is a special kind of elevator that will take us up into space.
• The easiest way to plot decimals and percentages on the number line is to convert them into their respective fractions.
• The scarcity of water is a real problem on Earth. But it is not necessary that we also find an alternative source of water on any other planet. So we should use water very carefully.

## Let’s Discuss

• Where were we going? Why?
• How did we decide to go to planet Mobo?
• How did the distance meter show the journey?
• Draw your own number line of a journey and plot fractions, decimals and percentages.
• Do you waste water? Have you taken any measures to avoid water wastage?