Alex-

Today, I sat in a car which was using a Global Positioning System known as GPS. It uses signals sent from satellites revolving around the Earth’s orbit to provide directions to the driver. To understand more about the launching of these satellites, we need to understand speed and angle

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Shubha-

As we look around on speedometers inside the cars and the sign boards showing speed limits, we find that everywhere speed is written in “mph”; which stands for miles per hour. Since we know that distance is measured in miles and time is measured in hours. Therefore, we infer that, somehow speed is dependent on distance and time.

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Sahana-

Let’s explore how the speed of a rolling bathroom roll is related to the distance traveled by it in a fixed time.

(Kieran and Cameron help.)

1. First we will mark the starting line. (Kieran marks it with tape).

2. Then, a bathroom roll is pushed from the starting point with a large force (Kieran pushes the roll with a lot of force). After 5 claps its ending position is marked(Cameron claps and marks its end point). The number of foot spaces between the starting and the ending points (Kieran measures it as x) is found to be x.

3. The same exercise is repeated with lesser force (pause till this exercise is completed). This time the number of foot spaces between the starting and the ending points (Kieran measures it as y) is found to be y.

4. In this experiment 5 claps represent the fixed time and the number of foot spaces measures the distance. Since x is greater than y. Therefore, fast speed implies more distance covered in a fixed time.

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Max, Lucas and Ismael- (Loudly together) – GOOD TO KNOW THAT FAST SPEED IMPLIES MORE DISTANCE COVERED IN A FIXED TIME.

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George-

An angle is always between two straight lines. For example, it could be between two palms. The angle is zero degrees when the palms are together. The angle increases as the palms are opened up and becomes 90 degrees when the two palms form a right angle. Generally, all angles are with reference to the ground. For example, my body while standing straight makes a 90 degrees angle with the ground.

Another common observation is that the ball shot at an angle always follows a curved path.(Shubha throws the ball towards Alex).

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Cameron-

Let’s find out how the angle of shooting the ball changes with the distance from the basket.

(Shubha and Alex (as a basket stand) help)

1. We start with observing the angle of the arms with reference to the ground(show it) while shooting the ball standing closer to the basket.

2. Next we repeat the same exercise while shooting the ball standing far away from the basket.

3. We conclude that while shooting ,the angle of the arms with reference to the ground is larger when we are standing closer to the basket.

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Max, Lucas and Ismael (Loudly) – SOMETHING TO REGISTER, WHILE SHOOTING ,THE ANGLE OF THE ARMS WITH REFERENCE TO THE GROUND IS LARGER WHEN WE ARE STANDING CLOSER TO THE BASKET.

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Alex-

With this knowledge about speed and angle, I guess we can now understand how a satellite is launched.

If the speed is large and the angle of launching is small, the satellite will revolve in an orbit, further away from the Earth.

(George shows the launching of satellites on a hula hoop with Sahana's help).

If the speed is less and the shooting angle is large, the satellite will revolve in an orbit, closer to the earth.

(George shows the launching of satellites on a hula hoop with Sahana's help.)

Once the satellite is launched in the correct orbit, it sends the signals to a GPS receiver in the car; which in turn provides driving directions.

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Max, Lucas and Ismael (Loudly) – WOW, WE DID NOT KNOW THAT LAUNCHING OF SATELLITES IS BASED ON THE SAME PRINCIPLES AS SHOOTING THE BALL INTO THE BASKET.

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Shubha-

I think it’s really neat to know that apparently complicated launching of satellites is based on simple concepts of speed and angle. The concepts which can be understood while having fun with rolling the bathroom rolls and shooting the basket balls. It feels great to realize that the concepts of Physics can be explored without any textbook, equations or hi-fi equipments.

ABOVE ALL THE BEST PART IS TO KNOW THAT THE CONCEPTS OF PHYSICS CAN BE ABSORBED WITH LITTLE GUIDANCE AND MORE AWARNESS .

****

(Everyone comes together and takes a bow)

OTHER DETAILS

1. Only the words outside the brackets need to be spoken.

2. Also x and y will be determined on the stage, while doing experiments.

Vocabulary (need not memorize, just to know)

Orbit-An orbit is the path that an object makes around Earth under gravitational force.

Satellite-A satellite is an object which has been placed into orbit.

***

Aum Tat Sat (God is Truth)

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## Thursday, April 17, 2008

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