how do scientist measure air velocity?
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A hand held instrument called a velometer. It measures the pressure of the air against a tube and gives a digital readout. Feet per second, Meters per sec.
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You can use a spirometer to do it. Please check out this link I am giving you, it will solve your problem. They have really done it well\nhttp://intranet1.sutcol.ac.uk:888/NEC/MATERIAL/PDFS/HUM_BIO/AS_HUMAN/23U2_T2.PDF\n(We can measure the volume of air moved by the lungs using a. spirometer . The ... air min. −1. with a breathing. rate of 18 breaths min ...)- excerpt from the site.
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An anemometer is a device for measuring the velocity or the pressure of the wind, and is one instrument used in a weather station. The term is derived from the Greek word "anemos" meaning wind.\n\nAnemometers may be divided into two classes, (1) those that measure the velocity, (2) those that measure the pressure of the wind, but as there is a close connection between the pressure and the velocity, a suitable anemometer of either class will give information about both these quantities.\n\n\nCup anemometers\nThe simplest type of anemometer is the cup-anemometer, invented (1846) by Dr. John Thomas Romney Robinson, of Armagh Observatory. It consists of three or four hemispherical cups, mounted one on each end of a pair of horizontal arms, which lie at equal angles to each other. A vertical axis round which the cups turn passes through the center of the arms; a train of wheel-work counts up the number of turns which this axis makes, and from the number of turns made in any given time the velocity of the wind during that time is calculated. The cups are placed symmetrically on the end of the arms, so it is easy to see that the wind always has the hollow of one cup presented to it; the back of the cup on the opposite end of the cross also faces the wind, but the pressure on it is naturally less, and hence a continual rotation is produced; each cup in turn as it comes round providing the necessary force. The two great merits of this anemometer are its simplicity and the absence of a wind vane; but if used without electronic data logging equipment it is not well adapted to leaving a record of the actual velocity at any definite instant, and hence it leaves a short but violent gust unrecorded. Unfortunately, when Dr. Robinson first designed his anemometer, he stated that no matter what the size of the cups or the length of the arms, the cups always moved with one-third of the velocity of the wind. This result was apparently confirmed by some independent experiments, but it is very far from the truth, for it was later discovered that the actual ratio, or factor as it is commonly called, of the velocity of the wind to that of the cups depends very largely on the dimensions of the cups and arms, and may have almost any value between two and a little over three. This had the result that wind velocities published in many official 19th century publications were often in error by nearly 60%.\n\nHot-wire anemometers\nHot-wire anemometers use a thermistor or other temperature measuring device heated up to some warm temperature. Air or other gases or fluids flow past the hot wire and cool it to a steady temperature, which depends on the flow rate. The change in resistance can be calibrated to changes in flows for a cheap way to measure flow rates.\nSonic anemometers\nSonic anemometers uses sound waves to measure wind speed and direction. They're capable of measuring the wind velocity in the X (east-west), Y (north-south), and Z (up-down) directions. Additionally, they can take measurements with very fine resolution, and the lack of moving parts makes them appealing to automated weather stations. Use of such anemometers is likely to increase in the future.\n\n\nWindmill anemometers\n \nAn aerovaneThe other forms of mechanical velocity anemometer may be described as belonging to the windmill type. In the Robinson anemometer the axis of rotation is vertical, but with this subdivision the axis of rotation must be parallel to the direction of the wind and therefore horizontal. Furthermore, since the wind varies in direction and the axis has to follow its changes, a wind vane or some other contrivance to fulfill the same purpose must be employed. An aerovane combines a propeller and a tail on the same axis to obtain accurate and precise wind speed and direction measurements from the same instrument. In cases where the direction of the air motion is always the same, as in the ventilating shafts of mines and buildings for instance, wind va
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With an anemometer is like three sticks with a little cup on each end, arranged at 120° at the top of a pole wich rotates faster or slower depending on wind speed. You can see them at ships and airports...
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If by "calculate" you mean process the results of experimental meaurements of speed, force, etc., then you measure the initial total energy (potential, kinetic) of the test object, measure all known energy input that occurs along the path (integral of applied external force times velocity dot product), and subtract from the total of those two the final total energy. The result is the energy lost to dissipative processes like friction and air resistance.\nIf instead you use calculate in the sense of predicting the dissipative losses, you need a model of the object (its drag coefficient and the coefficient of friction). If the path is constant-slope and speed and air density are constant, you can calculate the end state analytically because drag force is constant and so is normal force and thus friction. Otherwise you have nonlinearities which require a time-stepped simulation to solve.
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If you mean air speed - it is measured in knots.\nIf you mean altitude it is measured in metres.\nIf you mean distance flown - kilometres
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The simplest way is spectography. if you are speaking of a breathalizer test it is via conductivity.
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I don't know about using a pendulum, and the ballistic gelatin is too inconsistent for accurate velocity measurements.\n\nI use a chronometer. VERY simple device - there are two photoreceptors placed a set distance apart, both with white screens above them to serve as a backdrop. Any object passing across the first photoreceptor starts a timer, and the timer stops when that object passes the second receptor. Because the distance is known, the chronometer is able to calculate velocity.\n\nAn inexpensive ballistic chronometer will set you back about $90-$100. add features like multiple shot memory, printers, or large LCD displays and the sky's the limit!
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Theres a tool called a Handheld Anemometer, amazon has one inexpensive
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The main question is what do you want to test for? I can't imagine you'd get much useful out of a wind tunnel since generally people are concerned about range and how straight a paper airplane would fly.\n\nIn a wind tunnel, you are mostly looking for forces and moments acting on the airplane at various speeds. If you are looking for these kinds of things, then a wind tunnel is really the only way.\n\nThe issue then becomes how to attach the paper airplane to the measurement apparatus. If you are only looking at drag, then a string on something should be ok if you do some quick calculations. If you want more, you'll need a solid attachment to a force and moment balance which will be very difficult to do. You will need to stiffen your paper airplane and figure out a good, not too invasive way of  attaching it to the balance.
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Atmospheric pressure and physics
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It weighs the amount that the air inside it weighs.
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air resistance.\n\n Do the experiment yourself- if at school- get a teacher to make up a sealed tube, suck out the air (less difficult than it sounds- i remember doing something like this) and then invert it. its very strange.
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A Psychrometer is the general name for instruments designed to determine the moisture content of air. A psychrometer consists of dry-and wet-bulb thermometers that give the Dry-and Wet-bulb Temperatures, which in turn are used to determine Relative Humidity and Dew Point.
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Measured from the ground, its speed is = the car speed + the fly speed measured inside the car.\nThe fly can fly so fast because the air inside the car is steady.\nIts the same if you walk inside a train, your speed measured from the ground will be= the train speed + your speed measured from the train. This doesn't mean you can walk so fast, the train floor is steady.\nIt all depends from the reference point you are measuring. Imagine what the speeds would be if you measure them from outer space, results would be totally different.
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Manometers are used to measure pressure. It's basically a u-shaped tube with a liquid in the bottom (usually water or mercury) and it is sealed on one end. As the pressure increases, the liquid is pushed up into the sealed end. By graduating the tube, you can use it to measure presure.
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The density of air, ρ (Greek: rho) (air density), is the mass per unit volume of Earth's atmosphere, and is a useful value in aeronautics. In the SI system it is measured as the number of kilograms of air in a cubic meter (kg/m3). At sea level and at 20 °C dry air has a density of approximately 1.2 kg/m3. varying with pressure and temperature. Air density and air pressure decrease with increasing altitude.\n\nThe formula for the density of air is given by:\n\n P=p/R*T\nwhere ρ is the air density, p is pressure, R is the gas constant, and T is temperature.\n\nThe individual gas constant R for dry air is:\n\n R( dry air )=287.05J/kg*K\nTherefore:\n\nAt standard temperature and pressure (0 °C and 101.325 kPa), dry air has a density of ρSTP = 1.293 kg/m3. \nAt standard ambient temperature and pressure (25 °C and 100 kPa) dry air has a density of ρSATP = 1.168 kg/m3. \n[edit]\nEffect of water vapor\nFor moist air, the partial pressure of the water vapor must be considered as well. In this case, the density of the air is the sum of the density of the dry air and the density of the water vapor:\nP=pdry air /Rdry air*T+p water vapour/R water vapour*T\n \nThe gas constant for water vapor is:\nR water vapour=461.495 J/kg*K\n \nEffects of altitude\nTo calculate the density of air as a function of altitude, one requires additional parameters. They are listed below, along with their values according to the International Standard Atmosphere, using the universal gas constant instead of the specific one:\n\nsea level atmospheric pressure p0 = 101325 Pa = 1013.25 mbar or hPa = 101.325 kPa (= 101325 kg/(m*s2)) \nsea level standard temperature T0 = 288.15 K \nEarth-surface gravitational acceleration g = 9.80665 m/s2. \ndry adiabatic lapse rate L = −0.0065 K/m \nuniversal gas constant R = 8.31447 J/(mol·K) \nmolecular weight of dry air M = 0.0289644 kg/mol \nTemperature at altitude h metres above sea level is given by the following formula (only valid below the tropopause):\n\n T=To+L*H\nImportance of temperature\nThe below table demonstrates that the properties of air change significantly with temperature.\n\nTable — speed of sound in air c, density of air ρ, acoustic impedance Z vs. temperature °C\n\nImpact of temperature \n°C c in m/s ρ in kg/m³ Z in Pa·s/m \n- 10 325.4 1.341 436.5 \n- 5 328.5 1.316 432.4 \n0 331.5 1.293 428.3 \n+ 5 334.5 1.269 424.5 \n+ 10 337.5 1.247 420.7 \n+ 15 340.5 1.225 417.0 \n+ 20 343.4 1.204 413.5 \n+ 25 346.3 1.184 410.0 \n+ 30 349.2 1.164 406.6