Appspiration , is that a word ? If it is, it should mean inspired by an app.
I have always enjoyed tinkering around with tools and enjoyed making something. This joy has recently been put to use in order to make projects for my school going son. As the years go by, the nature of the subjects he is studying is becoming more interesting so making models out of those is a fun filled activity for me.
This year the topic was force.
Earlier in the year my company released an iPad app for science, called Xperica HD (Full disclosure : I manage the development of that app). This app features interactive experiments covering a few topics in Physics. During the development of this app, i learnt quite a bit about those topics, much more than when i was in school.
This is when i was appspired.
I decided to take one of the experiments featured in Xperica and make it into a physical model.
The selection of the experiment was the first hurdle, any of the 10 experiments could be made into a model but would the model be interesting and meaningful ? After much deliberation, i settled on the experiment involving pulleys. The idea was to show how the use of pulleys can reduce the need for muscular force. On one hand, the model had to be made and on the other, the my son's team needed to be educated on the model so they could present it in their school.
After going over the various elements in my mind with several options, i sketched out a rough idea as to what the model may look like. Since there were weights involved and force, i know the basic frame had to be tough. I went to a construction site i knew where wood work was going on and got a hold of one of the carpenters. With his help,i was able to make a strong rigid frame of wood that could take quite a punishment, if needed.
There were going to be 2 systems for comparison, one with a single fixed pulley and the other with one fixed and one movable pulley. The system with the movable pulley would need much lesser effort to lift the same amount of weight than the single pulley system. At least that was the theory. I myself had never expreienced a comparison of this sort. The two systems would be built side by side on my wooden frame for easy comparison. Each of the systems would have a 1 KG weight suspended on one side and the string could be pulled to move the weight.
Next up, i cannibalised my sons mechanical modeling set to build the pulley system. Using the basic pieces it provided, i made my pulley frames and fitted them on the wooden frame. Next up was the acid test, would the double pulley system actually feel lighter on the load ? Absolutely :) . While pulling the two strings you could certainly feel the double pulley system had a major advantage.
But how could i make this even clearer and visible ?
I decided to attach spring scales to each of the pulley systems so one could visibly make out the force applied on each. Finding spring scales was another matter. After a couple of days of searching both on the real world and on Google, i found a vendor who dealt in wholesale supplies of scales including spring scales. But i wanted only 2. After some explaining and cajoling on the phone i managed to convince them to sell me just the 2. Although they were located in a different city from me, it wasnt too far. Without wasting any time, i dashed to their warehouse location and picked up my scales :).
Once i got back home, i attached them to my model and was thrilled to see the double pulley system was using almost half the force and the single pulley system. Mission accomplished.
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