G ET LESS WET By Tilman Guenther, Grade: 7 Orefield Middle School Mrs.Kakaley

P ROBLEM S TATEMENT If you have to go a certain distance through the rain, at what speed and body posture will you get the least wet? Run like the wind! Lean forward and run Become Superman!! ? ? ? ?? ? ? ? ? ? ? ? ? ? ? ? ? ? ?

B ACKGROUND I NFO What is Rain? Rain is Condensation of atmospheric water vapor that falls under gravity. Distance / Time = Speed [cm] [sec] [cm/s] Water density = 1g / cm 3 Rain intensity Drizzle1 mm/day Light Rain2.5 mm/hour Mod. Rain10 mm/hour Heavy Rain50 mm/hour Violent Rain>50 mm/hour Formulas Volume = mass / Density [cm 3 ] [g] [g/cm 3 ] Rain volume [cm 3 ] Area [cm 2 ] x Time [sec]

H YPOTHESIS If having to go a certain distance through the rain, then running and slightly leaning forward will get you the least wet.

V ARIABLES Independent: Posture Independent: Speed Dependent: Weight Controlled: Distance Wind is not something that I added to the test.

S ETUP E XPLANATION Overflow Water uptake Water Bin Water pump Motor and Pulling system

M ATERIALS Setup Materials: Work bench 1.5m Water basin 1m x 0.2m Track 1.2m Rail car for track Frame to hold basins Model Human (absorbent) Twine Motor & control Garden hose to refill Testing Materials: Rain gauge Timer Scale / balance to determine wetness

B UILDING THE R AIN T UNNEL

S ETUP

P ROCEDURE 1. Turn on Rain 2. Wait five minutes 3. Test Rainfall 4. Weigh Model 5. Set Variables 6. Run Test 7. Weigh Model 8. Record Data Test Rainfall every 5 runs

D ATA T ABLES Run#PostureSpeedTimeWetness [deg][cm/s][sec][g] Wetness vs. Speed (Posture: 0) Wetness vs. Speed (Posture: -45) Wetness vs. Speed (Posture: -22) Wetness vs. Speed (Posture: 22) Wetness vs. Speed (Posture: 45) Run#PostureSpeedTimeWetness [deg][cm/s][sec][g] Wetness vs. Speed (Posture: 0) Tested five postures three times at five different speeds Performed 85 runs total Carried out 26 calibration runs

R AINFALL C ALIBRATION Pre-Calibrations Calibrations between tests Surface area 34.6 cm 2 60 sec Volume gram Rain intensity

W ETNESS C OMPARED TO S PEED ( CONSTANT POSTURE )

W ETNESS C OMPARED TO S PEED O BSERVATIONS ( CONSTANT POSTURE ) Observations: 1.The faster you go the less wet you get 2.This is true until a certain point; if you go any faster, you will still get wet equally

W ETNESS C OMPARED TO P OSTURE ( CONSTANT SPEED )

Observations: 1.When you don’t lean, you will get the least wet 2.If you need to lean, lean forward

A NALYSIS Top Wetness Variables: 1.Top Surface area Constant 2.Time & Speed of run Variable (distance constant) 3.Rainfall Intensity Constant The longer you stay in the rain, the wetter you will get from the top Wetness Speed (= 1 / time)

A NALYSIS Front Wetness Variables: 1.Distance Constant 2.Front surface area Variable 3.Rainfall Density Constant As long as you do not stand still, distance is connected directly with wetness Wetness Speed

A NALYSIS C ONCLUSION Wetness Speed Wetness Speed Look familiar??

A NALYSIS C ONCLUSION My Java simulation rain calculator application

C ONCLUSION The purpose of my experiment was to discover what speed and posture will get you the least wet when running though the rain. My original hypothesis was that running and slightly leaning forward is the option to get the least wet but I was wrong, fast speed is good, but leaning causes more wetness. The only error that occurred was when the holes where the rain came out were clogged but I realized this in time and no harm was done. If I did this again I would test additional variables such as wind speed and direction, rain droplet size, and rain intensity.

B IBLIOGRAPHY Background Water "Why raindrops are different sizes." USGS. USGS, 8 Feb Web. 23 Oct Physic book (hypertextbook.co,) Building the rain tunnel No refs found! Lots of experimentation Similar experiments (not as good Thorough Savage, Adam, and Jamie Hyneman. Mythbusters: Running in the Rain MiniMyth. Discovery Channel, Discovery videos. Web. 24 Oct < mythbusters-running-in-the-rain-minimyth.html>.