How much more power do you think that you can generate with your legs than your arms? First, estimate the answer.
Then, look up the answer in David Gordon Wilson's paper "Understanding Pedal Power" (PDF) (Courtesy of David Gordon Wilson. Used with permission.)
In the lab, how much power were you able to generate using your arms? How much power were you able to generate using your legs? How do these values compare to each other, to your estimate of the power difference, and to the actual difference? If the result of the lab showed that the difference between your arms and legs did not match the common, documented difference, hypothesize the reasons for the discrepancy.
If we were able to harness the power that you generated and use it to power LEDs, how many of the LEDs that we provided to you would you be able to power using your arms? What about your legs?
As a class that focuses on design as well as energy, it is important for you to start thinking about where the technologies that you will be exposed to in this class can be applied. In order to start you on this path, review instructions for each pump:
For each pump:
Another commonly used pump in the developing world is the IDE India Treadle Pump. Read this treadle pump case study:
How does this treadle pump compare to the cement pump?
In the shop introduction, you were exposed to and trained on a variety of tools, some of which may have been new to you. However, as part of the design process, it is important to consider which tools and techniques our target communities will likely have access to. It would not, for example, be appropriate to have a critical component in your design be something that needs to be waterjet cut (though an experienced metalworker may be able to cut a similar component using a chisel). For both the cutting and drilling parts of the shop intro, discuss the different techniques you were exposed to paying particular attention to:
First, write down your impressions of each method of carrying water. Rank the methods from easiest to hardest for you. What are the pros and cons of each method?
If you had to carry 5 gallons of water a mile every day, and a q-drum was not available, which method would you use?
Now, read the following abstracts
If you find them intriguing, it's easy to get the entire paper online through the libraries; many of the citations are also interesting.
Did the findings from these papers in terms of the efficiency of the methods described surprise you or match your experience? Why?
Propose some reasons – from a physics standpoint – why the efficiencies of the methods described might be so superior.