What is Air resistance: Definition and 415 Discussions

In fluid dynamics, drag (sometimes called air resistance, a type of friction, or fluid resistance, another type of friction or fluid friction) is a force acting opposite to the relative motion of any object moving with respect to a surrounding fluid. This can exist between two fluid layers (or surfaces) or a fluid and a solid surface. Unlike other resistive forces, such as dry friction, which are nearly independent of velocity, drag force depends on velocity.Drag force is proportional to the velocity for a laminar flow and the squared velocity for a turbulent flow. Even though the ultimate cause of a drag is viscous friction, the turbulent drag is independent of viscosity.Drag forces always decrease fluid velocity relative to the solid object in the fluid's path.

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  1. O

    Plotting Height vs Time for an Object Under Air Resistance

    If I wanted to make a graph of height versus time for an object under the effects of air resistance av+bv^2 and thrown with a given initial speed, how would I go about doing that? I was also hoping to get a y versus x graph for a projectile under the same drag, but I presume I could find x...
  2. P

    Projectile motion air resistance calculator - tutorial?

    Projectile motion air resistance calculator - tutorial?? I am not familiar with the terms/words of physics in English, but I hope you can excuse me. I need a tutorial for how to calculate the air resistance in a projectile motion. I want to do it with my calculator and that's why I came...
  3. M

    Free fall with air resistance, must find velocity

    Homework Statement The problem is to find the velocity as a function of time, given the following; the object is in free fall and its initial velocity is zero. The formula given for the air resistance is: a = g - kv, where g is acceleration d/t gravity, k is a constant, and v is velocity...
  4. A

    Question to find speed at terminal velocity with mass and the air resistance

    On a recent drop, one of the parachutes holding a supply package didn’t open. If the mass of the package was 35 kg and the drag or air resistance factor was 0.8 kg/m, at what speed did the package reach terminal velocity? I am confused with this question mainly because of the unit used for...
  5. H

    How Can Air Throw Distance for Fans Be Calculated?

    Hello Everybody. I have a problem. I study calculate air throw distance for FANs. How can I calculate it? So I have some data below. Fan Diameter Volumetric flow rate (m^3/h) Temperature RPM Power Please send me note or documents If you have any. Thanks for your help.
  6. J

    Air resistance on moving ball?

    Homework Statement For a given tennis ball: Experimentally quantify the frictional effects of air resistance on a moving ball, including data needed to compute... (1) the frictional force on the ball; (2) how much of the ball's energy is lost to air resistance as it moves a certain...
  7. E

    Understanding the Role of Air Resistance in Solving Complex Scientific Problems

    Homework Statement all information is on picture Homework Equations The Attempt at a Solution I read the paper and understood it but when I got to the first question I was really confused. I do not even know what the problem is asking. This problem could give me an A in the class...
  8. D

    Sliding object against air resistance, working out when object comes to rest

    Homework Statement A sledge of mass m = 85 kg has initial velocity v0 = 45 m/s and is moving horizontally along a straight line. The net force acting on the sledge is solely due to air resistance and is given by F = −k v2, where the constant is given by k = 1.2 kg/m. Find where the sledge...
  9. F

    Total energy of an airplane, work done against air resistance

    Homework Statement An airliner of mass 300 tonnes is powered by four engines, each developing 15 000 kW. Its speed at take-off is 75 m(s^1), and it takes 11 minutes to reach its cruising speed of 210 m(s^1) at a height of 10 000 metres. Calculate the work done against air resistance during...
  10. Z

    Projectile motion with air resistance using Euler's method

    Homework Statement Calculate the trajectory of our canon shell including both air drag and reduced air density at high altitudes so that you can reproduce the results in Figure 2.5. Perform your calculation for different firing angles and determine the value of the angle that gives the...
  11. H

    Perturbation with equations of motion for air resistance

    Homework Statement "A ball is tossed upwards with speed V_0. Air resistance is -mkv^2 and there's gravity too. Find the the time it takes the ball to reach the maximum height. Do not solve the equation of motion exactly. Use the perturbation method on the equation of motion. Solve the equation...
  12. A

    Calculating Air Resistance in Falling Objects

    Homework Statement an object with a mass of 1.21g is falling at a constant velocity of 1.1 m/s. What is the force of air resistance exerted on the object? Homework Equations f=ma The Attempt at a Solution i imagined that if the object is falling at a constant velocity, then acceleration is...
  13. C

    Air resistance - find Vx(t) and Vy(t)

    Suppose at time t= 0 the football is kicked with initial velocity components Vxo and Vyo. Solve the equations above to find Vx(t) and Vy(t). You can make use of the formulas we worked out in class. "Equations above": ax = -kvx ay = -g-kvy formula worked in class: v(t) =...
  14. D

    How Do You Calculate the Diameter of a Parachute Needed for Safe Landing?

    Homework Statement An ideal parachute accelerates all the air it sweeps as it travels, and the air is accelerated from 0 to the parachute's velocity. Using F = dp/dt calculate the force on an ideal parachute of area A as a function of its velocity and the density of air. Assuming you wouldn't...
  15. C

    How Do You Calculate Air Resistance in a Simulation?

    Hi, I am currently working on a computer simulation of free falling objects with air resistance..and I am having problems computing for air resistance..can you give me the formula on how to compute it and an example please?..thank you :))
  16. S

    Projectile Motion with Air Resistance

    Guys, Hello, I am a high school student who has just started basic calculus and would like to know how to find the motion of the projectile taking air resistance into account. (The range, time, etc)(I have learned about projectile motion without air resistance) Please help me.
  17. A

    Ball thrown with air resistance

    This question is bothering me much, please answer in detail. For example if you throw a ball with initial speed (air resistance exists!) with an angle from horizontal. 1) Does it take more time for ball to reach its maximum height or to fall from maximum height to ground. 2) What...
  18. S

    Effect of air resistance on angle yielding max displacement

    Considering simple projectile motion, would the effect of air resistance cause the angle for maximum horizontal displacement to change? Would the maximum angle then be greater or less than 45 degrees? Just a conceptual question, don't really need equations (though wouldn't mind either).
  19. A

    About air resistance in horizontal direction

    Hello, I was playing with formulas on air resistance and derived formula for velocity in horizontal direction after object was thrown. It looks reasonable but I started have confusion about it, i'd like for you great experts check on its derivation, so here it goes every v is v in x direction...
  20. B

    Free Fall: Understanding Conditions & Air Resistance

    Hello, I was wondering under what conditions does free fall need to comply to in order to take effect? I am pretty certain that for an object to be in free fall it needs to be void of any friction, but what about air resistance? Or is air resistance a form of friction? Thank you in advance.
  21. S

    Space ship design idea, how to approach with out air resistance

    ok so here is what i was thinking when a spaceship enters the atmosphere the reason for the high impact velocity is that the air is spinning at 66000mh AND that to keep an orbit you need certain speed with is different from the Earth's rotation... now if you slow down/speed up to match...
  22. K

    Particle falling in earth's gravity with air resistance.

    Homework Statement A particle falls in Earth's gravity. The force of air resistance is F = −αv v where v is the velocity, v is the speed, and α is a constant. (The direction of the force is opposite to the velocity, and the magnitude of the force is αv2.) If the terminal speed is 20.2 m/s...
  23. W

    Kinetic friction, air resistance, and effect of velocity

    Hi, So I've read that kinetic friction does not depend upon velocity, but that air resistance does depend upon velocity. I hope those two statements are correct from the get go. I can see why the force of kinetic friction does not depend upon speed using a simple thought experiment. You...
  24. U

    Projectile Motion and Air resistance

    I'm taking grade 12 physics and I've been given a lab that involves a slingshot. A baseball will be shot using a slingshot and is to go 40m. I have to perform calculations to find out the initial velocity it needs to travel a distance of 40m, however, I have to take air resistance into account...
  25. Z

    Projectile motion with air resistance and earth

    Homework Statement A projectile near the Earth's surface (in 2 dimensions) is subjected to a resistive force F=-bv. The corrected value for time of flight is? (take r=b/m and initial velocity along y direction as Vo)The Attempt at a Solution Let instantaneous velocity vector V = Vxi + Vyj Let...
  26. N

    Ball and air resistance (curiously difficult)

    Hi, I was wondering in my physics class the other day, whether if you throw up a ball from a height say h with velocity v0 , facing air resistance Fair=-bv on its way up and down, would it reach its initial height h again faster or slower than if you were to throw it up in a vacuum (i.e...
  27. P

    How Do You Calculate Air Resistance for Projectiles in Excel?

    My teacher wants me to use an excel spreadsheet to show the difference in the movement of projectiles using air resistance. Can anyone help me with the equation for air resistance? Thanks, Peter G.
  28. I

    Magnitude of the average force of air resistance on a rocket

    Homework Statement An engine supplies an upward force of 9.00N to an initially stationary toy rocket, of mass 54.0g, for a distance of 25.0m. The rocket rises to a height of 339 meters before falling back to the ground. What was the magnitude of the average force of air resistance on the...
  29. M

    Initial acceleration of a projectile incl air resistance

    Homework Statement Conditions: (ii)x0 =0 and v0 =20ms−1 with a mass of 1 kg with c1 = 0.2kgs−1 and c2 = 0.02kgm−1 projectile is fired directly up (only considering motion in the EDIT y direction (previously x by mistake)) at 20m/s given eqn can calculate acceleration at the n+1 term (i.e 1...
  30. C

    Falling body with air resistance

    What is the difference between these two equations. m dv/dt = mg - kv and m dv/dt = mg - kv^2 as the equation modeling a falling body with air resistance?
  31. I

    What is the equation for air resistance?

    Homework Statement I would like to know if there is an equation/formula to find out the air resistance of any falling/moving object. This will be used in a simulator in a project I'm doing. I've looked around and all I can find is 'Do Experiments', 'Wind Tunnels'... This is not useful for...
  32. AlexChandler

    Air Resistance and Projectile Motion

    Homework Statement An object is ejected straight up into the air at an initial velocity v0. (a) Determine the time for reaching the maximal elevation when the object is subject to gravity alone. (b) Determine the time for reaching the maximal elevation when the object is subject to gravity...
  33. E

    What is the Work Done by Air Resistance on a Round Trip?

    Homework Statement A bicyclist rides 1.32 km due east, while the resistive force from the air has a magnitude of 6.12 N and points due west. The rider then turns around and rides 1.32 km due west, back to her starting point. The resistive force from the air on the return trip has a magnitude...
  34. O

    Momentum update with air resistance

    this isn't really a homework question but yaa its just a question. how do you integrate the air resistance formula into the momentum update formula??F Fair = C*\rhoA*v^2 and the momentum update formula is Pfinal=Pinitial +Fg\Deltat i used Fg instead of Fnet becuase in my situation i have...
  35. E

    Box slides down incline, air resistance does work. Find Velocity.

    Homework Statement A 38.7g box slides down an incline of height 12.5m. As it slides, air resistance does -3.71J of work. Find the speed at which it reaches the bottom of the incline. Homework Equations E kinetic at bottom = E potential at top - Work air resistance 1/2 mv2 - 1/2...
  36. P

    Parabolic shot with air resistance question

    hello At the moment, I have two questions. the first would be about air resistance, and the second about parabolic shots. 1) what is the best formula to calculate the air resistance of a basketball? 2) If I use parabolic shot, air resistance would only affect the X-axis but not the Y-...
  37. T

    Spring on a tilted table with air resistance

    Homework Statement an object of .4kg is attached to a spring with given spring constant 400 N/m. it is moving on a tilted table, that is at 30 deg from teh horizontal. The table is frictionless, but there is a dampening force -bv proportional to velocity. when the object is driven, the...
  38. R

    Magnus effect and Air resistance

    I was wondering which of these air resistance or magnus affect plays a role in the distance traveled by a ball more for a top spinning ball my thoughts would be that with both these effects the distance of the ball would travel less Please answer my question to satisfy my curiosity :D
  39. B

    Trajectory of a projectile WITH air resistance?

    ok. I'm a sophomore in high school who knows nothing about differential equations except for what wikipedia and some other sources said. I seem to simply have the need to figure this out. I've been to wikipedia, which didn't help. Could someone please provide a walkthrough on how to the math...
  40. S

    Finding the Force of air resistance

    A 1967 Corvette has a weight of 3020 lbs. The 427 cu-in engine was rated at 435 hp at 5400 rpm. a) If the engine used all 435 hp at 100% efficiency during acceleration, what speed would the car attain after 6 seconds? b) What is the average acceleration? (in “g”s). ans... a) 120 mph b)...
  41. B

    How Is Distance Calculated in Free Fall with Air Resistance?

    D=Drag Coefficient p=Density of air A=Cross sectional area v=velocity a=acceleration F= force F air=(DpAv^2)/2 F net=mg-F air ma=mg-F Air a=g-(DpAv^2)/2m k=DpA/2m so a=g-kv2 dv/dt=g-kv2 dt=dv/g-kv2 using the online integrator from wolfram we got...
  42. A

    Does the acceleration of free fall take air resistance into account?

    Homework Statement Does the acceleration of free fall take the effect of air resistance into account or is it equal to the acceleration of free fall on Earth if the Earth was in a vacuum? Thanks Homework Equations The Attempt at a Solution
  43. F

    Calculating Deceleration of Man on Bicycle with Air Resistance

    Homework Statement A man on a bicycle, of total mass 100 kg, is free-wheeling at a constant speed of 15ms^-1 down a hill with a gradient 10% (i.e. sin^-1(0.10)). He wants to slow down to a safer speed, so he applies the brake lightly to produce a constant braking force of 84 N. The air...
  44. J

    Help with an air resistance problem.

    Part A) A raindrop of mass 1.06 × 10−5 kg falls in air and reaches a terminal speed of 4 m/s. The acceleration of gravity is 9.8 m/s2 . What is the value of the constant k that determines the resistive force F = k v ? Answer in units of kg/s Part B) If there were no air resistance, how...
  45. B

    Projectiles launched at an angle, neglecting air resistance

    Homework Statement 2 Problems that I am unable to solve: 1.) projectile launched at an angle 35 degrees, just clears a wall 20m high at a distance of 130m from launch. Solve for initial velocity, time it takes the projectile to reach the wall, and the velocity components + speed of the...
  46. U

    Solving Air Resistance in Projectile Motion

    Homework Statement Suppose we attempt to account for air resistance in our projectile motion in the following (incorrect) way: we alter g so that the acceleration in the y direction is -8 m/s2, and introduce a horizontal acceleration of -3 m/s2. With these changes, find the landing point of a...
  47. B

    Initial speed of object sliding to a stop w/ air resistance

    Hey guys, I'm looking to calculate the initial velocity of a large object sliding to a stop over a surface. This is easy without the drag force of the air, but I'd like to include that to prove a point in my research. As a quick background, I haven't done a differential equation in over a...
  48. B

    Speed of object sliding to a stop w/ air resistance with respect to position

    Okay, first a brief intro. I studied math/physics extensively as an undergrad...but that was over 10 years ago now. My day job keeps me doing more basic physics and math regularly, but I haven't, for example, solved a differential equation in over a decade! Anyway... I'm trying to...
  49. J

    Understanding the Impact of Reduced Air Resistance on Object Acceleration

    If F is the force of air resistance on an object with mass m moving at a constant velocity, which of the following best describes the acceleration of the object when the force of air resistance is reduced by a factor of 4? F=ma It says the answer is equal to (3/4)F/m = a Can...
  50. J

    Report on air resistance of projectile motion

    Homework Statement All right, I'm doing a report for school that is due this friday and so far i have built a trebuchet, which is nearly irrelevant as I am prepared to invent results to match my report. Basically what I want to do is have an idea on where to go/what to do for my report, I...
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