Mass+and+Spring+Clock

=Clock Design: Simple Harmonic Motion= Date of Publication (Date of Most Recent Edits)


 * Participants**: Chelsea Hart, Sean Hamilton, Ashley Murphy
 * Purpose**: The purpose of this lab is to design and characterize a clock that makes accurate time measurements in the range of 30 to 90s.
 * Lab Documents**: [[file:Simple Harmonic Motion.doc]]

** Studied Design Variable 1: **We changed the amount of mass, raising ad lowering it, attempting to get our frequency to be sixty bounces per minute. When we increased the mass, the frequency would decrease and when we decreased the mass, the frequency would increase. To perform our tests we would raise the clock roughly twenty centimeters (to the point where the springs were not stressed) and release. We began the timer at the lowest point of that first bounce. We measured to sixty bounces and recorded the time elapsed.
 * Brief Description Clock Design**: Our clock structure was shaped like a box, with four poles standing uprights, two crossed poles on the bottom corners, and four poles connecting them as a square at the top corners. We tied two 16.5 cm springs together with a short piece of string and tied them to a piece of the pole that was extended over the table's edge. We connected the masses together by hooking the hooks to the springs and to the bottom's of each other. To start the clock you raise the masses and spring up to the point where the spring is no longer extended. You then release it and begin the digital timer when the mass/spring reaches it's lowest point. Counting at the lowest point, stop the timer when you have reached sixty bounces. Sixty bounces should equal within one second from sixty seconds.
 * Specifications of Clock:** First we decided that we wanted our clock to consist of a mass and spring. Then we figured out how to calculate time with the number of times the weights went up and down and a timer for 60 seconds. We started to test out different masses of weights and would increase when 60 bounces went under 60 seconds and decrease when 60 bounces went over 60 seconds (for example, 1,500g took only 53.89 seconds to reach 60 bounces and 1,900g took 62.65 seconds to reach 60 bounces). After many tests, we determined that the best mass was 1,830g since the data always was +-1 second away from 60 seconds (shown in the first graph points 4-7). Once we found our constant mass, we decided to experiment with the distance we raise the springs. According to our data, the distance did not affect the number of times the clocked bounce because it still had a +-1 second result. The 5cm distance took 30.60 seconds yet the 15cm (3x farther) had 29.42 seconds. The accuracy in our clock was very well done by having the data close to the same and under 2% accuracy.
 * Design Variables:** We believed that mass and the distance the spring was pulled down before release would be important variable to our experiment. We believed that the heavier the mass the less frequent it would be, causing their to be higher time for a lower number of bounces. Our second variable that we tested was how far we pulled the spring and masses down before releasing them to measure the frequency. We believed that the farther we pulled it down, the higher the frequency would be because the speed would be increased.


 * Studied Design Variable 2:** For the second variable we looked at the effect different release heights would have on the frequency. Due to our effective mass of 1830 grams, the frequency stayed the same no matter what height the clock was released from. To test this variable, we would raise the clock various heights (5cm, 8cm, 10cm, 12cm, 15cm, 18cm) and release, measuring the frequency with the stop watch. [[image:distance_raised_to_release_graph_chelsea.JPG]]
 * Lab Questions ** : Write out and answer any questions that are included as a part of the lab.
 * 1) Describe in detail how your device may be used to measure an event that lasts 60s. What would the accuracy of this measurement be? //The spring would be "loaded" with the masses. The spring would then be raised 20cm to the point where the spring is not stretched at all. The spring is then released and the timer begins at the lowest point of the first bounce. You will count 60 bounces and stop the timer at the lowest point of the last bounce. The accuracy will be within 1 second from 60 seconds.//
 * 2) Which variable that you studied had the most significant effect on the frequency/period of the clock? If you built your clock with a 20% increase in this variable, what would the new frequency/period of the clock be? Support your answer by referring to data in your report. //The variable that had the most effect on the frequency of the clock was the mass. If the mass were increased by twenty percent, it would be 2196 grams, which would decrease the frequency by roughly twenty percent, causing sixty bounces to take roughly seventy-two seconds, or forty-eight bounces to take roughly sixty seconds depending on how you want to look at it. Our data involving a mass of 1500 grams (eighteen percent less than 1830 grams) resulted in a six second difference in the times, which correlates with a roughly eighteen percent increase in frequency.//
 * 3) Which variable that you studied had the least significant effect on the frequency/period of the clock? If you built your clock with a 20% increase in this variable, what would the new frequency/period of the clock be? Support your answer by referring to data in your report. //The Design Variable 2 was how high the mass was raised from the lowest point it naturally sits. If this variable was to be increased by twenty percent from 18cm it would be raised to 21.6 cm. If it were raised to this height, it would take roughly 27.04 seconds for the clock to measure thirty bounces.//
 * 4) Though it was not a project requirement, it would be nice if your clock could also measure much longer times, on the order of 10 to //, it was a percent increase.//15 minutes. Would your clock design still be accurate for long time measurements? What might affect the accuracy of the clock for these longer measurements? Can you think of a way to improve the design to make the clock more accurate for longer measurements? //If the mass and spring clock was to be used to measure longer times, such as 10 or 15 minutes, the accuracy would not be as close. The reasoning is that when the clock is started, raised to the point where the spring is not compressed and then dropped, it is at its fastest frequency. Over time, the initial force of the mass decreases, causing the frequency to decrease, also causing the accuracy to decrease with time. This was seen while measuring the time it takes for sixty bounces in that within the first 15-30 seconds the clock was a second or two ahead of the watch, but when it came to a minute, it was less than a second// (+/-) //from sixty bounces. If the clock was to measure longer times rather than shorter, the mass would have to increased. From the graph of Design Variable 1 it is seen that an increase of mass makes the time it takes for the amount of 60 bounces more accurate; therefore, we would need to increase the mass before it was possible to measure 10 to 15 minutes because of the amount of force that would be needed to have the clock keep bouncing for that amount of time.//

Our clock proved to be valid and reproducible because of it's accuracy of always being close to a second away from the allotted time (whether it was 30 seconds or 60 seconds) and was able to repeat itself after many tests. One problem that occurred was how the two springs would connect together during the experiment that, if fixed somehow, could of improved our data. Another thing to always to consider is human error such as not stopping the stopwatch at the exact moment, All in all, we believe this experiment for us was a success and helped us understand better the relationship of time, distance, and mass.
 * Conclusion**:

> > //Don't forget to link to your lab report from the lab reports page and to include a link to your lab report in your reflection.//
 * Independent reflection:** One lab report will be turned in for each group. In addition, each student must complete //independently// a reflection addressing the following questions:
 * How was the process of designing and testing a clock similar to the scientific method as discussed in class?
 * How did it differ?
 * What "steps" in the scientific process were present and which were missing?
 * Was there a part of the activity that is not a part of the scientific process?