Sarah RoseLab 5: Wind Tunnel ExperimentsQuestion 1Our experimental value of n was n=1.9763. This value is less then 2 meaning the errors we due to wind speeds measured higher than actual wind speeds (Condition A) and/or pressure was measured lower then actual pressure (Condition D). The inaccurate wind speed could be caused by the positioning of the pitot tube and the anemometer. Holding the anemometer too far away from the end of the wind tunnel or at an angle other then directly facing the source of the wind could effect the recorded wind speeds. Other potential errors could have come from the fact that the wind tunnel is not completely sealed. Air leaking out would effect this experiment by lowering the air pressure which is congruent with Condition D. Also the unrealistic wind simulation from the Variac might cause results that don’t match up with real life scenarios because wind doesn’t normally behave the way we treated it in this experiment. There was also potential for measuring errors when we upped the Variac settings, it is possible that we didn’t wait long enough to take the measurements and the pressure/wind speed were still in transition from one setting to the next. Question 2The type of miniature car we used was a sedan and it took 9 m/s of wind to push the car out of the tube. To convert 9 m/s to mph 9(2.3) = 20.7 mph which doesn’t seem like a wind speed capable of pushing over a car or even a human. Acording to this lab it would take 9(4) = 36 mph to turn over a car. This value of 20 mph seems much too low. Itwould take hurricane force winds to over turn or move a car that size and 20.7 mph winds are associated with a breeze that barely move trees. It would take 80+ mph winds to move something like a car and those most likely occur with hurricanes. Once big difference between the lab model and real life is the difference in friction. In real life the frictional layer is a large factor for wind speeds, in the wind tunnel there is hardly anything to cause friction except the objects we measure. Also there is no geography in the experiment like in real life. Also the tunnel’s simulation of wind isn’t realistic, normally wind doesn’t come shooting from one position unceasingly. Question 3Our measured wind speed when the Variac was set to 30 was 5.1m/s. To convert that to mph take 5.1(2.3)= 11.73 mph. To scale this we then multiply that sum by 10. 11.73 mph (10) = 117.3 mph.The greatest negative pressure we recorded was -66 Pascal’s. -66(100)= 6,600 Pascals. To get the wind pressure in pounds per sq. ft. take 6,600(0.021) = 138.6 p.s.f. Question 4A 10 x 10 section of roof is 100 square feet. Using the pressure from question 3 we know that the pressure being exerted on the roof is138.6 p.s.f. (100 sq. ft) = 13,860 Pascals.If we want to see how many lbs of force is acting on a 100 sq footroof we take 13,860(0.021) = 291.06 lbs. ft. sq. this gives us how muchforce is on 1 sq foots. For all 100 sq. feet we multiply 291.06(100) = 29,106 p.s.f. That amount of pressure would destroy a regular roof. Summary and Conclusion In this lab we explored the relationship between wind speed and pressure. The questions revolve around bringing our lab findings to reallife applications. While our results weren’t completely congruent with real life examples they did a good job of showing the relationship between pressure and wind speed especially on structures. Reasons why our numbers might have been off maybe be due to the positioningof the equipment and the fact the wind tunnel had leakage. There could have also been loose attachments of the rubber tubes that could account for error. Our results for wind speed seemed fairly accurate, but our pressure seemed to be slightly lower then normal (Condition D). This lab helped me better understand the way pressure and windact upon an object. When the pressure on the hut became negative that mean that the force was pushing outwards on the roof and vice versa when the pressure was positive. It would take a storm capable of winds 60+ to cause damages toroofs. Storms like tornadoes, hurricanes and wind storms that generatestrong winds and/or gusts are likely to cause damage. Any thing considered ‘sever weather’ refers to any dangerous meteorological phenomena with potential to cause damage, serious social disruption or loss of human life. Thunderstorms, downbursts, lighting, tornadoes, waterspouts, tropical cyclones, and extra tropical cyclones are all knowto cause damage. Hurricane-force winds, caused by individual thunderstorms, thunderstorm complexes, tornadoes, extratropical cyclones, or tropical cyclones can destroy mobile homes and structurally damage buildings with foundations. Winds of this strength due to downslope winds off terrain have been known to shatter windows and sandblast paint from cars. Once winds exceed 135 knots (250 km/h) within strong tropicalcyclones and tornadoes, homes completely collapse, and significant damage is done to larger buildings. Total destruction to man-made structures occurs when winds reach 175 knots (324 km/h). Maybe houses with inverted roofs would decrease the