GET LESS WETBy Tilman Guenther, Grade: 7Orefield Middle SchoolMrs.Kakaley

PROBLEM STATEMENT

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!!

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BACKGROUND INFO

What is Rain?

Rain is Condensation of atmospheric water vapor that falls under gravity.

Distance / Time = Speed [cm] [sec] [cm/s]

Water density = 1g / cm3

Rain intensity

Drizzle 1 mm/day

Light Rain 2.5 mm/hour

Mod. Rain 10 mm/hour

Heavy Rain 50 mm/hour

Violent Rain >50 mm/hour

Formulas

Volume = mass / Density [cm3] [g] [g/cm3]

Rain volume [cm3]-------------------------------Area [cm2] x Time [sec]

HYPOTHESIS

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

VARIABLES Independent: Posture

Independent: SpeedDependent: Weight

Controlled: Distance

Wind is not something that I added to the test.

SETUP EXPLANATIONOverflow

Water uptake

Water Bin

Water pump

Motor and Pulling system

MATERIALSSetup Materials:Work bench 1.5m Water basin 1m x 0.2m Track 1.2mRail car for track Frame to hold basins Model Human (absorbent)TwineMotor & controlGarden hose to refill

Testing Materials:Rain gaugeTimerScale / balance to determine wetness

BUILDING THE RAIN TUNNEL

SETUP

PROCEDURE

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

DATA TABLES

Run# Posture Speed Time Wetness

  [deg] [cm/s] [sec] [g]

         

Wetness vs. Speed (Posture: 0)

1 0 6.24 10.00 9.86

12 0 6.50 9.69 10.01

6 0 6.55 9.60 9.64

2 0 12.80 4.89 5.93

8 0 13.00 4.83 4.86

13 0 13.00 4.82 5.01

9 0 18.70 3.36 3.46

3 0 19.50 3.21 3.66

14 0 19.80 3.17 3.17

15 0 25.50 2.46 2.64

10 0 26.20 2.39 3.30

4 0 26.50 2.37 3.66

16 0 30.90 2.03 2.13

11 0 31.00 2.03 2.80

5 0 31.50 1.99 2.58

7 0      

         

Wetness vs. Speed (Posture: -45)

32 -45 6.05 10.40 20.93

27 -45 6.18 10.10 18.99

49 -45 6.31 9.97 19.89

50 -45 12.20 5.12 11.60

28 -45 12.50 5.04 15.98

33 -45 12.80 5.10 13.11

51 -45 18.50 3.39 8.49

29 -45 18.80 3.34 9.83

34 -45 19.70 3.18 7.75

52 -45 25.50 2.50 6.47

35 -45 25.70 2.45 6.07

36 -45 26.30 2.38 6.19

30 -45 26.50 2.37 5.99

31 -45 29.80 2.11 4.89

53 -45 31.40 2.00 5.96

         

Wetness vs. Speed (Posture: -22)

70 -22 5.93 10.60 15.99

42 -22 6.16 10.20 14.64

65 -22 6.17 10.20 16.61

43 -22 12.20 5.13 8.06

66 -22 12.20 5.15 9.45

71 -22 13.00 4.84 9.21

67 -22 18.50 3.40 7.09

72 -22 19.30 3.26 5.92

83 -22 19.80 3.16 5.97

68 -22 25.30 2.48 5.00

84 -22 25.80 2.43 5.11

73 -22 25.80 2.44 4.76

85 -22 27.90 2.25 4.69

74 -22 30.40 2.07 4.64

69 -22 30.70 2.05 4.49

         

Wetness vs. Speed (Posture: 22)

37 22 6.32 9.95 17.29

60 22 6.35 9.91 17.73

54 22 6.52 9.66 16.77

38 22 12.70 4.93 9.11

61 22 13.00 4.84 7.19

55 22 13.10 4.00 9.70

62 22 19.40 3.32 5.06

56 22 19.80 3.17 6.22

39 22 20.30 3.09 5.50

63 22 25.90 2.42 3.67

57 22 26.60 2.36 3.72

40 22 27.20 2.29 3.62

41 22 28.70 2.19 2.72

59 22 30.70 2.04 3.49

64 22 31.00 2.00 3.41

         

Wetness vs. Speed (Posture: 45)

44 45 6.11 10.30 25.11

22 45 6.33 9.94 22.40

17 45 6.53 9.64 20.86

23 45 12.40 5.07 11.98

45 45 12.40 5.07 11.51

18 45 13.10 4.79 9.73

46 45 18.50 3.39 7.55

24 45 19.30 3.25 7.50

19 45 19.70 3.18 6.22

47 45 25.50 2.47 5.28

25 45 26.20 2.39 5.11

20 45 26.90 2.34 4.61

21 45 31.10 2.02 4.08

26 45 31.10 2.09 4.04

48 45 32.40 1.94 4.19

         

         

         

58        

75 0 147.00 0.42 1.78

76 0 174.00 0.36 1.77

77 0 98.70 0.63 1.64

78 0 116.00 0.54 1.54

79 0 53.50 1.17 2.06

80 0 100.00 0.63 2.19

81 0 58.30 1.00 2.40

82 0 112.00 0.56 1.88

Run# Posture Speed Time Wetness  [deg] [cm/s] [sec] [g]         Wetness vs. Speed (Posture: 0)

1 0 6.24 10.00 9.8612 0 6.50 9.69 10.016 0 6.55 9.60 9.642 0 12.80 4.89 5.938 0 13.00 4.83 4.86

13 0 13.00 4.82 5.019 0 18.70 3.36 3.463 0 19.50 3.21 3.66

14 0 19.80 3.17 3.1715 0 25.50 2.46 2.6410 0 26.20 2.39 3.304 0 26.50 2.37 3.66

16 0 30.90 2.03 2.1311 0 31.00 2.03 2.805 0 31.50 1.99 2.58

• Tested five postures three times at five different speeds

• Performed 85 runs total

• Carried out 26 calibration runs

RAINFALL CALIBRATION

1 2 3 4 5 6 7 8 9 10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

0

20

40

60

80

100

120Calibration Runs

Run #

Ra

infa

ll A

mo

un

t [g

]

Pre-CalibrationsCalibrations between tests

Surface area 34.6 cm2

60 sec

Volume

85.034 gram

Rain intensity

WETNESS COMPARED TO SPEED(CONSTANT POSTURE)

0 20 40 60 80 100 120 140 160 1800

2

4

6

8

10

12Wetness versus Speed

Speed [cm/s]

We

tne

ss [

g]

WETNESS COMPARED TO SPEED OBSERVATIONS(CONSTANT POSTURE)

0 20 40 60 80 1001201401601800

2

4

6

8

10

12Wetness versus SpeedObservations:

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

WETNESS COMPARED TO POSTURE(CONSTANT SPEED)

-45 -30 -15 0 15 30 450

2

4

6

8

10

12Wetness vs. Posture

Posture [deg]

We

tne

ss [g

]

WETNESS COMPARED TO POSTURE(CONSTANT SPEED)

-45 -30 -15 0 15 30 450

2

4

6

8

10

12Wetness vs. Posture

Posture [deg]

We

tne

ss [

g]

Observations:1. When you don’t

lean, you will get the least wet

2. If you need to lean, lean forward

ANALYSISTop WetnessVariables:1. Top Surface area ------ Constant2. Time & Speed of run ------ Variable (distance

constant)3. Rainfall Intensity ------ ConstantThe longer you stay in the rain, the wetter you will get from the top

Wetness

Speed (= 1 / time)

ANALYSISFront WetnessVariables:1. Distance ------ Constant2. Front surface area ------ Variable3. Rainfall Density ------ ConstantAs long as you do not stand still, distance is connected directly with wetness

Wetness

Speed

ANALYSIS CONCLUSION

Wetness Wetness

SpeedSpeed

Wetness

Speed0 20 40 60 80 100120140160180

0

2

4

6

8

10

12Wetness versus SpeedLook familiar??

ANALYSIS CONCLUSION

My Java simulation rain calculator application

CONCLUSION

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.

BIBLIOGRAPHY

BackgroundWater"Why raindrops are different sizes." USGS. USGS, 8 Feb. 2011. Web. 23

Oct. 2011. http://ga.water.usgs.gov/edu/raindropsizes.html Physic book (hypertextbook.co,)

Building the rain tunnelNo refs found!Lots of experimentationSimilar experiments (not as good Thorough

Savage, Adam, and Jamie Hyneman. Mythbusters: Running in the Rain MiniMyth. Discovery Channel, 2003.

Discovery videos. Web. 24 Oct. 2011. <http://dsc.discovery.com/videos/

mythbusters-running-in-the-rain-minimyth.html>.