Exploring Speed

MOTIVATION

While teaching Physics at San Jose State University a few years ago, I realized that the majority of 18 to 22 year old students did not have clear fundamentals. I felt as if I were watering the leaves instead of the roots. Then, I remembered that I personally had got interested in physical sciences and exploring my surroundings right around the age of 9. After about 3 decades later, I feel that Physics is happening everywhere, be it at the basket ball court or at the water fountain.

As seen by me, Physics is simpler than those complicated equations. It is more beautiful than the words that describe it in most of the text books and much more magnificent than those magic-tricks being shown by teachers to get a "Wow" (out of students) at different levels of education. All these ways are important in learning the subject, but I think the “essence of physics” gets lost in the equations, the text books and the magic tricks. I feel Physics (or perhaps most of the science subjects) really needs to be observed, probed, analyzed, assimilated and believed. I believe that for a balanced and complete understanding, the fourth leg of "exploring the surroundings" needs to be added to the existing techniques of teaching.

Following my passion about teaching Physics in its-simplest-form at the "right age" and my intention to do something for the school where my 9 year old daughter is studying. I talked to my daughter’s class teacher and he thankfully gave me an opportunity to do something I had wanted to do for a long time.

AIM

My aim was to make some 9 and 10 year old students understand the concept of “speed” without expecting any prior knowledge about the topic or the mathematical expression (“speed = distance/time”).

INTRODUCTION

To accomplish this goal, I, my 9 year old daughter’s classmates and their teacher worked as a team of researchers.

We started out by talking about common observations on the freeways. How, we often see a car moving faster or slower than the other cars on the freeway. How the car which seems to be moving faster, crosses the approaching exit earlier than the other cars.

In addition we talked about the sign boards showing the speed in "mph" which stands for miles per hour. We discussed that the "mph" written on speedometer and on sign boards provided us a lot of information. Each one in our team was aware that “miles” is used when talking about the distance covered and “hour” is used when one is talking about the time taken to cover a certain distance. Therefore, we knew that somehow, speed was related to “distance” and “time”. “How”, was the question to be addressed?

To accomplish this, we (as a team) came out into the basket ball court. The students formed pairs. Then they picked up a bathroom roll (one for each pair) and a piece of chalk. Then they marked two straight parallel lines (using chalk) on the ground about two leg spaces apart. These lines became the start and finish lines for their experiments.

EXPERIMENT #1

For this experiment, one of the students got ready to start rolling the bathroom roll from the start line towards his partner (sitting on the finish line).

In the first half of this experiment, the student pushed the roll faster (i.e. with more force), while his partner counted 1,2,3,4,… and noted the count (in a notebook) when the roll crossed the finish line.

In the second half of this experiment, the same exercise was repeated, but this time the student pushed the same roll (from the same starting line) slower (i.e. with less force), while his partner counted 1,2,3,4,5,6,7… and noted that count (in a notebook) when the roll crossed the finish line.

At the end of this experiment, we all gathered together to discuss our observations. Everyone had similar results. We all agreed that to cover a fixed distance (between two lines), the fast moving roll took less time (lesser counts) than the slow moving roll. Everyone was convinced that the FASTER SPEED IMPLIED LESS TIME NEEDED TO COVER A FIXED DISTANCE.

Without their awareness, these 9 year old students had verified the inverse proportionality between speed and time.

EXPERIMENT #2

In the second experiment, the number of counts was kept constant (e.g., 4). This time the other student got a chance to push the roll from the starting line. While his partner got to do 3 things. The partner had (a) to speak aloud the counts till 4, (b) to mark the point (with chalk) at which the roll crossed the ground (at the end of the count of 4) and (c) to measure the foot steps between the starting and the marked point.

The student pushed the roll faster (i.e. with more force) and his partner marked the point on the ground where the roll crossed at the end of the count of 4. The partner also labeled it as “fast”. As a last step, he measured the number of foot steps between the starting and the point marked “fast”.

The same exercise was repeated by pushing the roll slower (i.e. with less force) this time. At the end of the count of 4, the student counting the “counts” marked the point as “slow”, where the roll crossed at the end of the count of 4. He then measured the number of foot steps between the starting and point marked “slow”.

When we discussed the results of this experiment, everyone once again had observed a similar pattern in their results. They all agreed that for a fixed time, the roll pushed faster (i.e. with more force) covered a longer distance than a slower roll. We concluded that FAST SPEED IMPLIED MORE DISTANCE COVERED IN A FIXED TIME.

Those bright and wise 9 year old learners had verified the direct proportionality between speed and distance.

CONCLUSION

We concluded that faster (in comparison to slower) implied that
(a) less time was needed to cover a given distance and
(b) more distance was covered in a given time.

This was the same as implied by “the much known” equation “speed = distance / time”.

It was a wonderful experience that day for me to able to make those 9 year old students grasp the concept of “speed” without using any equations, theory, demonstrations, gadgets or magic tricks.

ACKNOWLEDGEMENTS

I would like to thank Theodore (the teacher) for trusting me to do something “valuable and fun” for me. I would also like to thank each student for their cooperation and opening their “wisdom boxes” to explore speed. I appreciate Cheryl (the office administrator) for lending us those bathroom rolls.

WISHES

I pray that these students continue to “research and explore” things happening around them everywhere, by simply using their inherent-wisdom-boxes.

I wish that their parents/guardians provide them all the support in terms of time, space and encouragement to “nurture” a budding Newton in their family.

Happy Exploring,

Gunjan