Clock+Lab+Drew,+Jill,+Rachelle

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


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

media type="file" key="Block 1; Pendulum Clock.wmv" width="270" height="270" **Design Variables:** We thought the variables that would influence the clock were the mass, string length, and the angle the mass was dropped. The mass would affect the frequency by making the ocellations faster. The length of the string would affect the frequency because the longer the string the longer the time it takes to go back and forth and the shorter the string the faster it would go back and forth. The the angle the mass was dropped would affect the frequency because the farther you pull back the ocellations would be quicker and the less you pull back the ocellations would be slower. The first factor we studied was the length of the string. The results show that as the length of the string increases the number of ocellations in 30 seconds increases as well. To test this variable we used the same mass and angle dropped for all of the different string lengths. We used the mass and angle of drop as our control for the testing of this variable. As we changed the length of string we measured the number of ocellations it took in 30 seconds; we used a stopwatch to record the 30 seconds.
 * Brief Description Clock Design**: A single string attached at two points, on single rod, evenly spaced, with weight hangin in middle of string. Protractor also attched to rod in the middle to measure angle dropped from. Used stopwatch for purpose of measuring the time elapsed.
 * Specifications of Clock:** A single string with 500g of weight hung at 19cm. The string, in triangle form, had two points of the triangle tied 28.5cm apart on single rod. There was a protractor attched to rod in the middle (14.25cm) to measure the angle the weight was dropped from.
 * Studied Design Variable 1:** [[image:sting_length_rjd.JPG width="800" height="432"]]
 * Studied Design Variable 2:[[image:rjd_2.JPG width="800" height="434"]]**

The second factor we studied was the mass on the end of the string. The results show that as the mass on the end of the string decreases the number of ocellations in 30 seconds stays about the same. To test this variable we used the same length of string and angle dropped for all of the different masses. We used the length of string and angle of drop as our control for the testing of this variable. As we changed the mass we measured the number of ocellations it took in 30 seconds; we used a stopwatch to record the 30 seconds.

**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? **  To measure an event that lasts 60 seconds take a single string with 500g of weight hung at 19cm. Take the string and make into triangle form; the two points of the triangle tied on the rod have to be 28.5cm apart. Use a protractor attached to the rod in the middle (14.25cm) to measure the angle the weight was dropped from. Line the string up with the numbers on the protractor to so you can drop the weight from the angle of 30o. The accuracy of this measurement would be at least 95%, because the oscillations were within two to three seconds of 30 seconds every time we tested it. The variable that had the greatest affect on the clocks frequency/period was the length of the string. If we built our clock with a 20% increase in the length of the string then the frequency/period would be much less. The data shows that the length of the string made the oscillations slower as we tested it for 30 seconds. **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 variable that had the least affect on the clocks frequency/period was the mass. If we built our clock with a 20% increase in the mass then the frequency/period would not change. The data shows that as we decreased the mass it didn’t make a difference in the number of oscillations, so if we increased the mass it probably wouldn’t make a difference in the number of oscillations either. **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 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? ** We believe that our clock, with the way we designed it, would not hold up for a long period of time. The reason for this is, is because the number of oscillations would be less and it would become very inaccurate with one second equaling one oscillation. We think that if the angle of drop was much greater and we could use different materials such as wire instead of string, we could improve the accuracy of a long time measurement.
 * Lab Questions**:
 * 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. **

· ** A statement about whether you think that the experiment produced a valid and reproducible result and reasoning supporting your statement. **   We think that the experiment was valid and reproducible once we found a design that worked with one oscillation, one second. For our first tested variable we tested how the length of string affected the frequency and we found that it greatly affected the frequency. The second tested variable was how mass affected the frequency and we found that mass no matter how much you change it will not change the frequency outside the accepted range of 2-3 seconds. · ** A suggestion for a simple improvement to the experiment. Think about what caused problems, measurement inaccuracies, or inappropriate simplifying assumptions and propose a change. A sketch may be helpful. **  We think that a simple improvement to the experiment would be, if you gave us certain variables to study. Instead of having us come up with the variables and test them when they wouldn’t affect the frequency. 
 * Conclusion**: