Buggy Lab

Block 6 Group 1, Rebecca Harvey, Nick Chan, Aleksi Arostegui

Pre-Lab Notes:
-swerves left
-moves forward (position)
-lights up (flashes per sec)
-time

Focus on time and position -- IV/DV
Constant velocity (linear) equation: Xf =VT + Xo

Purpose: The purpose of this lab is to test the relationship between the time in second that the buggy is moving and its position as measured in meters.ok

Prediction: As the amount of time increases, the position of the buggy will increase proportionally.ok

Apparatus:

• Buggy
• Tape
• Meter stick
• Stopwatch/timer

Procedure:
1. Mark a flat area with tape to serve as the starting line. Make sure there is plenty of space in front of this line. This starting line is 0 meters.
2. Set the buggy directly behind the starting line, so that the front wheels are barely touching the edge of the tape.This buggy is facing a positive direction.good!
3. Ready the stopwatch.
4. Carefully, without moving the buggy, flip the start switch and start the stopwatch at the same time.
5. At five seconds, stop the buggy and use the meter stick to record its position.
6. Repeat steps 2-5, adding five seconds to the time each trial (10 seconds, 15 seconds, 20 seconds, etc.). Make 25 seconds your final time recorded, for a total of 5 trials.
7. Repeat all five trials, except start the buggy at -5 meters instead of 0 meters, still facing in a positive direction.good

Data Collection:
             Test 1                                                                    Test 2

Data Analysis: Test 1

Verbal Model: As the time in seconds increases, the position in meters increases proportionally.

Math model: position = 0.4748(meters/second)(time) - 0.28 meters

Slope: For every 1 second of time that passes, the position of the buggy moves by 0.4748 meters.

Y-intercept: When no time has passed, the position of the buggy is at -0.28 meters. This is close enough to 0 to be negligible.

Test 2

Verbal Model: As the time in seconds increases, the position in meters increases proportionally.
Math model: position = 0.4748(meters/second)(time) - 5.28 meters
Slope: For every 1 second of time that passes, the position of the buggy moves by 0.4748 meters.
Y-intercept: When no time has passed, the buggy's position is at -5.28 meters. This is close enough to -5 (the starting point) to be negligible.

Conclusion:
        The purpose of this lab was to test the relationship between the time in second that the buggy is moving and its position as measured in meters. In order to do this, we set up a starting point at 0 meters. We placed the buggy at this starting point and let it run for five second intervals. We recorded its position at each 5 second interval. We then created a starting point at -5 meters. We repeated the same tests, and recorded the data at 5 second intervals.
       We found that in both of the trials that as the time in seconds increased, the position in meters increased proportionally. We figured out a math model for the line of best fit for the first trail: position = 0.4748(meters/second)(time) - 0.28 meters. The second trial's equation was very similar: position = 0.4748(meters/second)(time) - 5.28 meters. Our slope for both trials was the same, at 0.4748 meters per second. This meant that in both trials, for every 1 second of time that passed, the position of the buggy moved by 0.4748 meters. This slope is the velocity of the buggy in both trials. The y-intercept represents the starting point of the buggy, or the initial position. Our y-intercepts were off by about 0.28 meters. This is about 2.5% error, and so within the general realm of error.good
       Our results supported our prediction, in that as the amount of time increased, the position of the buggy increased proportionally. This was true for both trials.
       The general physics equation derived form the x vs. t graph is Xfinal = velocity(time) + Xinitial. We got this from combining our regular y = mx + b equation with our math models to show velocity. The slope, again, represents the velocity, while the y-intercept represents the initial position.good
       In comparison with other groups, our results were very different at first glance, but when examined, we find that they weren't so different. Among groups, the average velocity recorded was about 45 cm per second. Ours was 0.47 meters per second. When you convert from meters to centimeters, you find that our results were similar. should we all have had same slopes?  why or why not?  However, with the second trial, there were several discrepancies. This is because groups were not performing the same experiment. Some groups started at different initial positions than we did, thereby affecting the final positions. Some groups moved in different directions, like we moved in a positive direction the entire time while some moved in negative directions. This leads us to conclude that with such different variables, the groups should not have gathered similar results in the second trial.
       Some sources of error include the fact that the buggy veered slightly to the left, meaning that it usually traveled a greater distance than we were able to measure accurately.excellent!   We could have changed our procedure to measure in a shorter amount of seconds, because the longer the buggy moved, the more off-course it veered, thus leading to more inaccuracy.perfect! Also, the reaction time from stopping the stopwatch and the buggy at the same time likely had a small effect, as it was unlikely that we stopped at exactly the right time. This is difficult to fix without some form of robotic help.ooh - coming soon!  just wait! There were probably discrepancies in measuring, because we had to stack meter sticks on top of each other. A tape measure would likely improve this aspect.
Distance -- how far something has traveled (path length)
Displacement -- change in position: Xfinal - Xinitial
Position -- location of something in relation to the origin (0)
Speed -- the measurement of how fast
Velocity -- speed and direction
        I enjoyed this lab because it was fun working with the buggies, and designing our lab's second trial was stimulating. In order to improve this lab I would suggest a shorter conclusion, because I feel like we covered all the necessary information in class or in our data analysis. yes  I know!  everyone hates the conclusion!  :)  great job!

Graphing Project

Block 6, Group 6, Rebecca Harvey, Aleksi Arostegui, and Blossom Wong

By Rebecca Harvey

Purpose: The purpose of the lab is to test how the height that a ball was dropped from would affect the bounce of that ball.

Independent Variable: The independent variable is the initial height (in ft) that the ball was dropped from. We chose this because it was easy to control and regulate.

Dependent Variable: The dependent variable is the highest point (in inches) that the ball bounced to. We chose this because it was easy to observe in its variations and use in calculations.

Controlled Variables: The dependent variables include the constant mass of the ball, constant conditions (no wind, even floor)

Summary: In this experiment, we set up a meter stick against a wall, so that the measurements would be accurate. We marked the heights that we were dropping the ball from (1 ft, 2 ft, 3 ft, 4 ft and 5 ft). We then held the ball at those marked heights and dropped it, without throwing it or using any sort of force. We carefully observed how high the ball bounced at each height and recorded it.

Photos:

Graph:

Analysis:

     Verbal Model: As the height in feet increases, the bounce in inches increases proportionally.

     Math Model: Bounce = 6.6 inches/feet (height) + 0.9 inches

     Slope: For every 1 foot in height, the bounce increases by about 6.6 inches.

     Y-intercept: When the ball is dropped from 0 ft above the ground (a.k.a. the ball is not dropped at all) it bounces about 0.9 inches. This data is significant enough to be problematic, meaning that our data is probably off. excellent work!

Spaghetti Bridge Lab

Block 6, Group 6, 8/27/13 Aleksi Arostegui, Blossom Wong, Rebecca Harvey
By: Rebecca Harvey

Pre-Lab Notes:

• Testing variables independently is essential
• Independent variable - variable purposefully changed by the experiment
• how many marbles, spaghetti strands
• Dependent variable - variable that responds to change in independent variable
• distance of cup from floor, how many marbles it takes to break (strength)
• Controlled variables - variables that stay constant
• bridge set-up (length of spaghetti, cup and string, books)

Purpose: Our purpose is to test how the number of thin strands in a spaghetti bridge will affect the strength of the bridge.


Prediction: If there are more strands of thin spaghetti in the spaghetti bridge, then the bridge will be stronger and able to sustain more weight.


Materials:

• Thin spaghetti strands
• Cup
• Marbles
• String
• Supports (table)

Procedure:

1.     Set up supports by pushing two tables together until they are 6 inches apart

2.     Attach the string across the top of the cup so that the cup hangs from the string.

3.     Place one strand of thin spaghetti evenly across the gap between the two tables. Put tape in the spots where the spaghetti is resting to mark the exact spot to place your bridge.

4.     Hang the cup from the center of the thin spaghetti strand.

5.     Place marbles in the cup, one at a time, until the spaghetti bridge breaks. 

6.     Record how many marbles it took for the bridge to break.

7.     Repeat steps 3-6 five more times, adding one more string of spaghetti to the bridge each time, for a total of six trials.

Data Collection: 

Data Analysis: great!

       Verbal Model: As the number of spaghetti strands in the bridge increases, the strength of the bridge increases proportionally.

       Math Model: strength = (4.5143 marbles/strand)(spaghetti) - 0.8 marbles

       Explanation of Slope: The slope means that one strand of spaghetti has the strength in order to hold, on average, 4.5 marbles, and for every 1 strand of spaghetti added to the bridge, 4.5 marbles are able to be sustained and added to the collective strength of the bridge.

       Explanation of y-intercept: The y-intercept means that when there are no spaghetti strands, the bridge can obviously support no weight, because the strength is zero. Our y-intercept as very close to 0, meaning that our data was very close to what it should have been.

Conclusion:

       The purpose of this lab was to test how the number of thin spaghetti strands in a spaghetti bridge would affect the strength of the bridge. In order to test this, we set up a bridge using thin spaghetti strands placed over a six inch wide gap between two tables. We then suspended a cup from the bridge by a string and placed marbles into the cup until the spaghetti bridge broke. We repeated this experiment five more times, each time adding a strand of spaghetti to the bridge.
       My prediction was that the more spaghetti strands in the bridge, the stronger the bridge would be. We found that this was an accurate prediction; as the number of spaghetti strands in the bridge increased, the strength of the bridge increased proportionally. We found the exact equation to be: (strength) = (4.5143 marbles/strand)(spaghetti) - 0.8 marbles. The slope, or 4.5143, meant that as the spaghetti increased by 1, the strength of the bridge would increase by 4.5143 marbles; that is, proportionally. Our y-intercept should have been at 0, due to the fact that a spaghetti bridge with no strands can support no marbles and therefore has no strength. However, -0.8 is very close to 0, meaning that our data was most probably very close to accurate.
       Our data was markedly different than many of our classmates'. This was to be expected, however, due to the fact that not everyone was testing the same variables with the same control groups. For instance, some groups used thin spaghetti, like us, but some used regular (thicker) spaghetti strands. We also used marbles as units of measurement while other groups used hex nuts. The distance between supports was not controlled across all groups, and some groups taped their bridge to the table, while we did not. This disparity in controlled variables across the groups led to very different results.
       Indeed, we should not have gotten the same results because each group was doing a different experiment when it came down to the details. In this experiment I learned that the details and the differences in "controlled" variables are extremely important in order to have consistent results. but the general trend was the same
       There are several small things that could have, and probably did, go wrong in our procedure. For instance, we did not account for the weight of the cup when calculating results. This weight would have affected the breaking point of the bridge, and therefore the results. We dropped the marbles in the cup from non specified heights. This was not only inconsistent, but by dropping the marbles instead of placing them gently in the cup, we likely added further stress to the bridge. And finally, it remains unlikely that all the spaghetti strands used in this experiment were uniform in thickness and strength. This would have affected the strength of the bridge, and is very difficult to measure. Out of all these errors, the dropping the marbles in the cup seems like the easiest to fix. With that example, we could focus, next time, on gently placing them at the bottom of the cup. The weight of the cup could be accounted for in calculations, however, it would still have an effect on the breaking point of the bridge. The inconsistency of the strength of individual spaghetti strands is the one error that is the least possible to fix, because there is no way of ensuring that each spaghetti strand is identical.  excellent!
       Proportionally - having a consistent ratio or relationship between two factors as they increase or decrease
       Trendline - a line on a chart that expresses and predicts the average movement of the variables being analyzed
       Variable - a condition or factor that can be manipulated, either by the manipulation of other variables or directly, to show change in a lab experiment
       This lab was extremely detailed, requiring everything to be written down exactly as the structure dictated, with very little room for exploration or unexpected results. It was a very predictable lab, with a rigid structure and very little spontaneity. I appreciated the simplicity of the procedure, but at the same time I felt like I was working very hard on something not very interesting. I realize that this was a tester lab, in order to familiarize us with the designated format, but I hope that in the future, there will be more opportunities to explore and be surprised by the scientific principles being demonstrated. I totally understand where you are coming from, and I think you'll like it better next lab!  :)  great job!