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                   Chapter Introduction | 
                    Web Resources 
                    | Assignment Comments 
                    | Teaching Materials 
                  The assignment in chapter 
                    6 asks you to design and evaluate a timepiece. This may sound 
                    daunting task, so we suggest here some issues that might help 
                    you when tackling it.  
                  The idea behind a clock is to communicate 
                    the time. Traditionally this has been done using an essentially 
                    round clock face (the surround may in fact be any shape, but 
                    having rotating hands inevitably results in an essentially 
                    round display). Digital watches which display the time in 
                    numbers bring a different kind of accuracy to time keeping, 
                    and also lend themselves to a different kind of design. 
                  Some design considerations: 
                   
                    
                      - What kind of watch is it to be: wrist, 
                        mantel, casement etc? This influences the size and the 
                        practicality of some designs.
 
                      - How accurately does the watch need to 
                        display the time? For a stop watch used in sports or in 
                        timing experiments, the timepiece needs to have great 
                        accuracy, down to tenths or hundredths of a second. However, 
                        for other purposes, the accuracy can be within one or 
                        two seconds, and in other cases within a minute may suffice.
 
                      - It needs to show a changing state, and 
                        this requires something to move. This can be achieved 
                        by having two shapes moving across each other (e.g. a 
                        sundial has essentially two shapes moving one over the 
                        other), or by the transference of a substance from one 
                        place to another, e.g. water going from one container 
                        to another, or light gradually increasing and decreasing 
                        in intensity.
 
                      - What will power the clock? This may be 
                        electricity, or mechanical, but it may also be solar or 
                        driven by a more unusual power source such as a potato 
                        or apple. (Yes, they do exist and they do work!)
 
                      - Also, take a look at this intriguing 
                        example of a clock design!
 
                     
                   
                    
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