Environment+and+safety

** Are different surfaces (stone tiles, red brick, relatively smooth rubber staircase, bumpy rubber track, grass turf) in a school (Taipei American School) on sunny and rainy days (wet and dry ground) dangerous for high school students in flip-flops? **

** Independent Va ﻿ riables ** Type of surface, and whether that surface is wet or dry.

** Dependent Variables ** The friction of a flip-flop on different surfaces and wetness levels. (Fake grass, rubber track, bricks, stone tiles, plastic stairs surface)

** Con ﻿ trols ** __Person pulling on the dual range force sensor__ - one person was in charge of pulling the sensor attached to the flip-flop, as the speed at which the flip-flop is being pulled needs to be approximately the same for all trials. Changing the person would result in a greater change of the speed, therefore effecting the resulting static fiction

__Distance the flip-flop travels (1 m__) - A meter stick was placed at the side of the flip-flop while being pulled to ensure all trials have the same length of surface for static friction to be recorded.

__Length of the string being used to attach the flip-flop to the sensor__ - This was kept at 50cm. Changing the length of the string would result in inconsistency in the data, as different string lengths could yield different static frictions

__Flip-flop__ - The flip-flop being used to test the friction on different surfaces and levels of wetness was kept constant, to isolate the independent variables from the dependent.

__Weight put on the flip-flop__ - The weight put on the flip-flop was used to create more friction, as the flip-flop itself is too light to yield meaningful results; and by using the same weight, the amount of normal force will also stay constant.

** Materials **
 * 1) Flip-flop, size seven (86.056 g)
 * 2) String (50 cm)
 * 3) 1 weight (1 kg)
 * 4) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Dual Range Force Sensor
 * 5) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Laptop with Vernier Loggerpro Programme
 * 6) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">1 Metre stick
 * 7) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Excess tap water (using a bucket, hose, or water bottle)

__<span style="background-color: #ffffff; font-family: Verdana,Geneva,sans-serif; font-size: 120%; vertical-align: baseline;">** Procedure ** __
 * 1) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Set up experiment: Tie a string connecting the flip-flop to the dual range force sensor. Hook a 1 kg mass weight to the flip-flop. Set up the Vernier LoggerPro Programme.
 * 2) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Go to the first surface (fake grass, rubber track, bricks, stone tiles, or plastic stairs). Place a metre stick on the ground. Drag the dual range force sensor with the flip-flop and weight for 1 metre, while recording the friction levels with the LoggerPro Programme. Perform 5 trials.
 * 3) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Pour water on the surface that was just tested and perform 5 more trials. Make sure the surface is constantly wet (i.e. if it absorbs water, or if it is at an uneven surface).
 * 4) <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Repeat the same process for all surfaces

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 11px; line-height: 17px;">

<span style="background-color: #ffffff; color: #008080; display: block; font-family: Georgia,serif; font-size: 20.8px; text-align: center; vertical-align: baseline;">

<span style="color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: 120%; line-height: 21px;">**Sample Graphs** Since the objective of the lab was to find the static friction, the data points we selected were the first instances where a "peak" is formed, as denoted by the red dots (the black circles are simply there to show the points clearly)

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">

<span style="color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: 120%;">**Data Table**

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 90%;">__Static Friction of Different Surfaces__
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Static Friction (N) || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 1 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 3 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Avg || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 1 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 3 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Trial 5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Avg ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Stone Tiles || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">11.6 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">11.4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.9 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.7 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.6 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.6 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">12.2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.6 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.1 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.8 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.8 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Red Brick Tiles || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">9.18 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">9.32 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">9.47 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.9 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.9 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">9.15 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.30 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.32 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.03 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.10 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">6.54 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.06 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Rubber Layered Staircase || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.50 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.50 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">3.56 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Rubber Track || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">15.1 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">13.2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">15.2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">14.4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">12.4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">14.1 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">13.00 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">12.2 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">11.4 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">10.5 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">12.0 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">11.8 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Turf / Fake Grass || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">6.91 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">9.15 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.84 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.00 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">6.49 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.50 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.06 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.3 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.13 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">8.03 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">5.67 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">7.44 ||

<span style="font-family: Verdana,Geneva,sans-serif; font-size: 90%;">__Averages of Static Friction Coefficient__ <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">1086.1g = 10.6N
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Friction Coefficient (N) || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Dry || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Wet ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Stone Tiles || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">1.00 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">1.02 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Red Brick Tiles || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.86 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.67 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Rubber Layered Staircase || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.8 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.34 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Rubber Track || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">1.33 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">1.12 ||
 * <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">Turf / Fake Grass || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.71 || <span style="font-family: Verdana,Geneva,sans-serif; font-size: 85%;">0.70 ||

<span style="background-color: #ffffff; color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: 120%; vertical-align: baseline;">** Sa ﻿ mple Calculations **

<span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Normal force = 1 kg mass + 0.086 kg flip flop = 1.086 kg

<span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Coefficient of static friction = static friction / normal force

<span style="color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: medium;">**Possible** ﻿**Errors**
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">The volume of water could have been different in other surfaces.
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">more than 5 trials were implemented for each variable, because sometimes the data seemed off, but only 5 data trials were used - could have affected the results/conclusion?
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Random leaves on the ground under the shoe

<span style="background-color: #ffffff; color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: 120%; vertical-align: baseline;">** Method Limitations **
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Selective data bias (re-trying data when the results were not reasonable)
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">Inefficiency - the actual procedure of the experiment only requires a maximum of three experimenters while six people were performing the actual experiment.
 * <span style="background-color: transparent; color: #000000; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-decoration: none; vertical-align: baseline;">The flip-flop was wet after being dragged on a wet surface, then used in a dry surface trial while it was still wet.

<span style="background-color: #ffffff; color: #c79c57; font-family: Verdana,Geneva,sans-serif; font-size: 120%; vertical-align: baseline;">** Conclusion **

<span style="background-color: transparent; color: #000000; display: block; font-family: Verdana,Geneva,sans-serif; font-size: 85%; text-align: justify; text-decoration: none; vertical-align: baseline;">According to the data, the lower the coefficient of static friction, the less safe it is for students to walk on that surface. The smooth rubber staircase had the lowest coefficient of static friction when it was wet (0.34 N), while the rubber bumpy track had the highest coefficient of static friction when it was dry (1.33 N). A possible explanation for this might be because the smooth rubber staircase did not absorb any water when it was wet and was relatively smooth surface, thereby creating a film of fluid. On the other hand, the track had an uneven and very porous surface with many small indentations, allowing water to seep into those spaces, retaining its roughness. The grass turf had the smallest difference in coefficient of static friction between wet and dry, perhaps because the small rubber particles under the fake grass absorbed much of the water and cleared the surface (that is walked on) of most of the water, making it less slippery. The surfaces that had more friction were less slippery and more safe to walk on when it was raining or not.Another area where potential errors could occur would be our interpretation of the graph. As the data points were often quite scattered and magnifying the graph proved a bit of a challenge, it was difficult to determine where exactly the first instance of static friction occurred. This could be improved by perhaps using a different, more precise software to graph the data points obtained from Logger Pro, or if we could somehow figure out a way to manipulate the graph for better results.