I am looking for the difference between air and water resistance.?
340597
there's not too much difference, other than  the density which causes the drag coefficient. however, water has surface tension, which may be slightly important in causing greater drag
989461
parachute is affected by two forces: weight and air resistance\nm.g weight is fix\nK.v² air resistance is proportional to:\n-square of speed\n-viscosity of air (eps)\n-projection of area of contact (A)\n-form coefficient (alfa)\nalfa is related to the dynamic for of the contact surface\nalfa is minimum [ex: 0.06] for best air design [like bullet]\nalfa is 1 for plan surface\nalfa is 6 for hemisferic surface\ndynamic relation:\nm.g-K.v²=mv';    v' is acceleration, which is derivative of speed\nv starts with 0 and m.g-K.v² starts with mg - 0=mg >0\nmv' starts =mg >0\nspeed increases as very quickly\nv increases so m.g-K.v² decreases\nso mv' decreases and the acceleration is decreasing, speed v is still increasing but slowly\nv continues to increase for several seconds until m.g-Kv² becomes 0\nwhen that comes, the acceleration becomes 0 and speed is fix = maximum speed.\n\nthat maximum speed is Vmax:   m.g-K[Vmax]²=0\nVmax=sqrt[m.g/K]\nthat is the speed of falling of parachute\nVmax=sqrt[m.g/(eps.A.alfa)]\nVmax is invers proportional to sqrt of projection of surface contact and sqrt of form coefficient.\nif the parachute is with same form, same surface contact its speed will not be affected by no. of strings neither by diameter. They almost have no contact with air
924970
Atmospheric Pressure VS Vacuum -- which is stronger?
820353
You've presented a paradox:  How can you have air friction in a frictionless world?  \n\nAir resistance and air friction are two terms for the same phenomena.
1087751
The amount of air is the difference in volumes.\nA = V(r+1) - V(r) = (4/3)pi (r+1)^3 - (4/3)pi r^3\nA = (4/3)pi((r+1)^3 - r^3)
975645
the particles of water are far more closely packed than the particles of air. air is mostly empty space and therefore with fewer particles colliding with your hand, its going to be much easier to move your hand through the air than water.
110828
Archimedes said: When an object is submerged in water, there is a buoyant force upwards on it that is equivalent to the weight of the water displaced. \n\nSo if you have a heavy object underwater, and it is displacing water, its net weight will be less than when it is in air, displacing air, which is much lighter, so has a much smaller buoyant effect.
25327
the biggest difference is the size of the water vapor in the air and the temperature difference between the ground and the air above it. fog occurs when either cool air passes over warm moist ground or warm wet air passes over cold ground. fog is also very small droplets of water with almost no weight. mist on the other hand can be produced by low hanging clouds that are filled with moisture, from higher clouds that are also filled with moisture but not enough to produce true rain, and yet another is extemely high wind can carry water vapor up in to the atmosphere until the wind dies which allows the water to fall back to the ground. mist is also heavier than fog but still lighter than a true raindrop. there are also various other ways to get mist instead of rain or fog, your best source would be NOAA for a scientific explanation.
1054158
I think the key words in your question are "at room temperature".  See, room temperature is less than body temperature.  Heat energy wants to go from a higher temp region to a lower temp region.  But, water absorbs heat energy at a faster rate than air.  So, the cooling feeling (or transfer of heat away from your body into the surrounding medium) is greater in water than in air.  Now, turn on a fan and have more air, thus more cooling medium moving over you taking heat away and it will feel cooler even inf the air is at the same room temperature.
905311
Air resistance is a force operating in opposition to thrust.  With a given thrust the object increases speed, which increases drag due to air resistance, until thrust and drag are equal at which point the object no longer accelerates.  This also applies if the "thrust" is gravity acting on a falling object -- it will reach "terminal velocity" when gravity has accelerated it to a speed at which the air resistance is equal to the weight of the falling object, at which point the forces are in equilibrium and the object neither increases nor decreases in speed.\n\nThe shape of an object affects air resistance -- generally speaking the greater the cross section and the flatter the leading and trailing edges are perpendicular to the direction of travel, the greater the air resistance and the lower the maximum velocity or terminal velocity that can be achieved.\n\nBy adjusting the shape of an object so that air flows around that object with the minimum of resistance, you decrease the drag and this in turn increases the maximum acceleration and speed.  It can alternately be used to increase efficiency as less thrust is needed to achieve the same accelerations and speeds.
561115
Question -   Please explain how molecules in the air cause air\nresistance. Why air resistance is larger when a car a travelling faster?\n---------------------\nSharazaad,\n\nEven though you cannot see them, air molecules (a mixture of gases, mainly nitrogen and oxygen) are \njust like all other molecules inasmuch as they have mass and occupy space. Anything moving through \nair must push the molecules out of the way.\n\nThe faster the object moves, the faster the air molecules are encountered and the greater are the \nnumber to be pushed aside. This requires a larger force that necessary when the object is moving \nslowly. Consider swimming: The faster you swim, the harder it is to push the water molecules out \nof the way.\n\nStreamlining a car is a way of making it slip through the air more easily. Cars with narrow or \nwedge-shaped front ends and smooth, gentle curves allow it to slip through the air more easily \nthan bulky things like large trucks with large, boxy, flat front ends. Even something so simple \nas keeping a car clean and polished will help it slip through the air more easily.\n\nRegards,\nProfHoff 869\n=====================================================\nSharazaad,\n\n\nMolecules in the air have mass.  Even though they are invisible, they are\nstill there, and they still have to be pushed out of the way for a car to\noccupy the space that the air is in.  This now should make sense WHY air\nresistance even exists.\n\nNOW.  Why do greater speeds cause there to be an even greater air\nresistance.  It is true that there is barely any appreciable air resistance\nto a car going 10 MPH versus 60 MPH.  But at 60 MPH, even though there is\nthe same amount of air, the resistance is much greater because the car needs\nto move the air out of the way MUCH MUCH QUICKER.  I do not know if you can\nreally speak about viscosity of air (non - liquid).  But air really does\nbehave like a liquid when it comes to resistance.  HOW?  The air that is\nexisting on or above the sidewalk WILL ALSO RESIST the air molecule that is\nbeing struck by your car and pushed to the side.  SO, this is why at higher\nspeeds you will have a much greater resistance because you are FORCING THE\nAIR to move not at 10 MPH but NEEDING IT to move out of the way at 60 MPH.\n\nYou could say that the relationship between air resistance (r) and velocity\n(v) is proportional.  However, I think I read somewhere that resistance (r)\nis ~ velocity (v)^1.5\n\nPlease do not quote me on that ... but I am pretty certain I read it in an\nMath book for Engineers.  So there may be some credence to it.\n\nHope this helps.\nDarin Wagner\n=====================================================\nAir resistance is caused by the car banging into air molecules and\nincreasing their momentum in the direction the car is going.  Since the car\nexerts a forward directed force on the molecule, by Newton's 2nd law (for\nevery action there is an equal and opposite reaction) the molecule exerts a\nforce on the car in the backward direction, tending to slow the car.\n\n\nOf course, a molecule has so little mass, it exerts an extremely tiny force\non the car.  However, there are so many molecules that the cumulative effect\ncan be large.  You might also imagine what would happen if molecules were as\nlarge as bowling balls!  I think you can picture how the forces could be\nvery large.\n\n\nIncidentally, the molecules are moving at speeds much faster than the car is\ngoing and in random directions.  So some hit the car from the rear and speed\nit up a little (very little).  However, one coming from the front slows the\ncar down by a larger amount because the car's speed is added to the\nmolecule's speed for a molecule coming from the front and subtracted from\nthe molecule's speed for one coming from the rear.\n\n\nBest, Dick Plano, Professor of Physics emeritus, Rutgers University\n=====================================================\nHi Sharazaad,\n\nGood question,
837489
neglecting air resistance I hope!\n\ny=1/2at^2+vot+yo\n\na=32 ft/sec^2   you did mean sec^2?\n\nalso, v=at+vo  so we can find vo from this at time 2.1s when v=0\n\nfinally we insert 2.9 s into the first equation (yo= 0 too right?).
810714
the velocity of fluid flow is proportional to area.\nfind the total area of one 4 mm tube compared to 2  mm tubes.  Here is a hint, they wont be the same.
286635
The magnitude of each force depends on a lot of factors. Gravititional force is constant as long as the mass of the object remains the same. Buoyant force depends on the the density of the fluid. If the fluid is plain old air, then the buoyant force is probably very small. But if the object were placed in water, it would have a significantly larger buoyant force. Fluid resistance depends on the surface area of the object, the speed of the object, the shape of the object, the mass of the object, and the density of the fluid. Fluid resistance may be large for a parachute but small for a penny. You could find all of these numbers and compare the forces to see which are larger.
350704
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.
1015592
An ampere is a measure of current -- how much electricity is passing through your wire at any given time.  An ohm is a measure of resistance -- how much is the wire resisting the flow electricity through the wire.  Although many electrical engineers frown on this analogy, I find it useful: Think of your wire as a big garden hose.  You turn on the water and charge the hose.  The water pressure is kind of analogous to voltage -- it's the difference between the pressure at the source and the open end of the hose, and is a measure of potential between the two points.  Amperage is kind of like flow rate -- how many gallons a minute are you getting out of that hose?  And resistance is a measure of the friction slowing the flow down, as well as any back-pressure if you stuck your finger over the end or if the hose develops a kink.  If you got a bigger hose, you could obviously move more water and it is less likely to get constricted (thicker wire means it can handle more amps, and has less resistance to flow) but you'd have to have a bigger pressure source to push that much water through it (needs a higher voltage to maintain the same level of current through a thicker wire)  Does that help?
832830
Your head loss is going to be the the total weight of the water columns (height X area X density) between the inlet and the outlet.\n\nThe height of the current point at freefall is the head required by the pump beyond the inlet pressure supply to provide the required pressure at the outlet. It is the pressure expressed as weight of the water column divided by the outlet area.\n\nE-mail me more specifics.