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. I

    Work done by Air resistance on ball?

    Homework Statement Hey! Problem: A ball falls 8,5 meters, and hits the ground with 11 m/s. The ball has a mass of 0,2 kilos. How much work was done by Air resistance on the ball? Homework Equations I guess mechanical energy eqution? The Attempt at a Solution answer should be -4,5 joule...
  2. F

    Help! Physics Problem: Find Theta for 1000m Target

    http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=4836&context=ujmm Ive been awake for thirty six hours and I don't know differential equations. Im trying to find the angle (theta) over the horizontal axis that is needed to hit a target that is 1000 meters away they are basically...
  3. F

    Ballistic Coefficients vs Drag Coefficients

    So, I'm currently writing a mathematical analysis of a bullet with a muzzle velocity of 790 m/s. I have found that the standard equation for drag force... Fd = 1/2 * ρ * v2 * Cd * A does not work because the drag coefficient for a bullet (.295) does not account for supersonic speeds. What I...
  4. M

    How do you do projectile calculations, but with drag force?

    And how do you find the drag force?
  5. S

    Terminal Velocity of a skydiver

    Homework Statement [/B] A skydiver, initially undergoing a high acceleration, is approaching her terminal velocity. At a given instant, the fluid friction (due to air resistance) on the diver and her diving gear is 680. N [up] and the unbalanced force causing the acceleration is 40. N [down]...
  6. M

    What caused the discrepancy in the bullet's travel distance at the firing range?

    In this clip the mythbusters are investigating projectile motion at a firing range: Using the fact that the bullet fell approximately 1 inch as it traveled 100 feet, I predicted it should travel 600 feet down the firing range before hitting the ground from a height of 36 inches. Instead, it...
  7. AdityaDev

    Air Drag & No Drag on a Ball Projected Vertically

    < Moderator Note -- thread moved from General Physics to Homework Help forum > If a ball is projected vertically upwards say with a velocity V. Case 1: Without air drag Case 2: With air drag What will be the difference in v-t graphs and the motion of the ball Air drag D=bv (b is a constant,v...
  8. J

    How does weight affect air resistance?

    How does weight affect air resistance? [i.e A heavy feather falling v.s a light one}Please be simple
  9. S

    Finding Force of Air Resistance on Parachutist Falling at 55km/h

    1. A parachutist of mass 62 kg is falling at 55 km/h when her parachute open. She then falls 24 m in the next 2.0 seconds. Find the force of air resistance acting on the parachute during those 2.0 seconds.2. Could I just find the force of friction?3. I found out what the force would be if not...
  10. M

    Cube Projectile Motion: Air Resistance & Cross Sectional Area

    We have a solid cube with some mass that we fire as a projectile at some angle. The cube is launched in such a way that two of the faces are perpendicular to the initial velocity vector. Assuming there is air resistance, would the cube change its orientation while it flies, even if the mass is...
  11. O

    Speed loss per second due to air resistance

    Is there a formula covering this? (not including free fall/gravity) I have the drag coefficient, velocity and every other variable I think I would need for the object in particular.
  12. R

    Solving for Velocity of Falling Object with Air Resistance

    An object with a mass if falling with a force that is equal to its own weight of 25 pounds. The air resistance causes a decelerate force equal to 1/2 the velocity of the object at any time. If the object falls from rest, what is the velocity of the object after 8 seconds? I'm just confused at...
  13. J

    Projectile Motion Neglecting air resistance

    Homework Statement Neglecting air resistance, if you throw a ball straight up with a speed of 20 m/s, how far will it be moving when you catch it? Homework Equations None The Attempt at a Solution
  14. M

    Ionized Air Resistance: Research & Questions

    i am doing a research about ionized air ,and i have little question how much electrical resistance ionized air have?
  15. H

    Air resistance, changing position in free fall?

    Let's say that I have a stick with weight evenly distributed throughout. I attach a fan to one end of the stick, then balance it from its new centre of mass. I measure the distance from the ground to the stick then drop it. The stick tilts up towards the side generating more air resistance (fan...
  16. M

    Classical Mech - Newtons 2nd. Quad Air Resistance

    Homework Statement A puck of mass m is kicked up an incline (angle θ) with initial speed vo. Friction is not present, but air resistance has a magnitude of f(v) = cv2. Solve Newtons second law for the pucks velocity as a function of t on the upward journey. How long does the journey last...
  17. Y

    Projectile Subject to Quadratic Air Resistance

    Homework Statement A projectile that is subject to quadratic air resistance is thrown vertically up with initial speed v0. (a): Write down the equation of motion for the upward motion and solve it to give v as a function of t. (b): Show that the time to reach th top of the trajectory...
  18. M

    How to model the flight kinematics of an airplane with air resistance?

    I want to derive some equations for a 2-D airplane's motion, specifically when it lifts off and lands. Can someone show me where I can start and how I can use differential equations to develop equations like the speed/position of the airplane in its x and y components? Also, if anyone is...
  19. matineesuxxx

    Projectile motion with air resistance

    Homework Statement Model the trajectory of a projectile with an initial velocity v_0 that is subject to the force of drag.Homework Equations F_{\text{d}} = \frac{1}{2}C_{\text{d}}\rho\text{A}(v(t))^2 v_x(t) = v_{0x} + \int_{t_0}^t a_x(t')\mathrm{d}t' The Attempt at a Solution I really...
  20. STEMucator

    Solving a Coconut's Fall: Speed, Work, & Air Resistance

    Homework Statement A coconut, with ##m = 2.30 kg##, falls from rest from a tree which is ##h = 35.0 m## high. Take ##g = 9.78 m/s^2##. 1. What speed does the coconut hit the ground? Ignore air resistance. 2. If it actually hits the ground with a speed of ##23.9 m/s##, how much work was...
  21. B

    Why Does It Take 200 N to Slow Down a 10 kg Mass in Free Fall?

    If a 10 kg mass is in free fall (no air resistance), what force must be applied to slow the object down? (g = -10 m/s^2.) For this question, why is it 200 N and not 100 N? Wouldn't 100 N cancel out upward and downward forces and cancel them out?
  22. B

    Understanding Air Resistance: Explaining the Math Behind Reduced Force

    Can someone please explain the math of this problem? -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? (a) F/m (b)...
  23. P

    Air Resistance of a Diver using Ek and Eg

    Homework Statement A 57.0 kg diver dives from a height of 15.0 m. She reaches a speed of 14.0 m/s just before entering the water. What was the average force of air resistance (e.g., friction) acting on the diver? What is the force of friction underwater if she reaches a depth of 2.5 m before...
  24. A

    Height of ball bounce with air resistance

    Homework Statement Ball with mass of 0.7 kg and radius 0.15 m is dropped from top of the building 30 m tall. Force of air resistance which acts on ball is given with the equation: F_r = \frac{1}{2} c S ρ v^2 where c = 0.5 S = r^2 ∏ ρ = 1.29 \frac{kg}{m^3} v = current speed. How tall will...
  25. patrickmoloney

    Drag Force - Air Resistance Question

    Homework Statement A skydiver drops o¤ an outcrop at the top of a sheer face on a mountain and falls vertically downwards. Let v(x) be the velocity of the skydiver at a vertical distance x below the drop-off point. As the skydiver falls he will experience a drag force of magnitude...
  26. Maxo

    Projectile with air resistance

    Grεετings! :smile: I have some questions about a physics problem. I would appreciate some help with understanding this. Homework Statement The task is to plot some graphs for a projectile at different angles, first when neglecting air resistance and then including a formula for air...
  27. Y

    Does Air Resistance Cause a Ball to Take Longer Falling Down Than Rising Up?

    Homework Statement If a ball is thrown upwards and lands in the same spot, would it take longer to reach max height or drop back down from the max height? Also use air resistance. Homework Equations The Attempt at a Solution I believe that it would take longer for the object to...
  28. D

    MHB Max distance when an angle for a projectile is pi/4 neglecting air resistance

    We know that the angle of \(\frac{\pi}{4}\) causes a projectile to travel its max distance when air resistance is neglected. When we consider air resistance is the \(\frac{\pi}{4}\) still the angle that produces the max distance? With air resistance, the projectile with of course travel less...
  29. S

    How does air resistance change with weight and surface area?

    Homework Statement This isn't exactly homework...but I'm not sure where to post it. I was reading a textbook, and got myself in a mental predicament. I understand the reasons the book gave, but I want to *really* understand. So my question: "Why does air resistance decrease as the...
  30. L

    Air resistance upon a spinning block

    I came up with this problem, and solved for it, but I do question its accuracy, and id like to know how I could make it a better model. (it is not a homework problem) So, a block, of dimensions a (rests on the z axis) by b (rests on the y axis) by c (rests on the x axis), is moving with a...
  31. J

    Does Cold air cause more Air Resistance?

    I know that Cold Air is more dense than the warm air, so for example: If a car was accelerating facing a hot air, it will face less air resistance. But if it was facing a Cold air, it will face more air resistance because the cold air contain more mass per volume for each particle. It will face...
  32. S

    Projectile motion of tennis ball with air resistance

    Hi, so I am trying to model the path of a tennis ball when serving. I already have the model without air resistance, but now I'm getting into differential equations with the air resistance. I obtained two differential equations for acceleration that i think are correct, but I'm not sure where to...
  33. E

    Calculating Terminal Velocity with Air Resistance: A Case Study in Free Fall

    My textbook source is: Fundamentals of Physics, 6th edition, by Halliday, Resnick, Walker According to Newton's well known 2nd Law of Motion: Fnet = ma In chapter 2, in the case of free fall, the Fgrav = mg, where g = -9.8 m/s2, assuming that movement along the axis of y is positive...
  34. A

    Air Resistance (Drag Force) and Terminal Velocity

    Homework Statement "How does air resistance affect terminal velocity" Homework Equations N/A The Attempt at a Solution I know most of the answer of this, however I am just wondering say take a parachutist for example, if the air resistance is the resultant force, then in order...
  35. U

    Work, Gravity and air resistance question

    Homework Statement A mass m is fired straight up from a cannon, through the air, it rises to a maximum height, and then it falls back down to its initial height. There is air resistance. Consider these three statement. I. The work done by the force of gravity during the flight is Zero...
  36. B

    Calculating Coefficient of Air Resistance

    Hello, For my Classical Mechanics Lab, my fellow students and I are to calculate the coefficient of air-resistance of several objects dropped from the roof of our science building. We are assuming that the air-resistance is linear in nature. The first method by which we calculate the drag...
  37. T

    Body thrown at angle to the horizon taking into account air resistance

    Hi every body! I'm a new guy here, and want to applologize for my Not perfect English. From the name of the topic you can understand what 'm trying to do here. ok here is an exercise: We have tennis ball m=57gr. and diameter of the ball D=6.7sm. from the start point coordinates Xo=0 & Yo=0.3m...
  38. B

    Solving for Position with Zero Initial Velocity

    Homework Statement Equation (2.33) gives the velocity of an object dropped from rest. At first, when Vy is small, air resistance should be unimportant and (2.33) should agree with the elementary result Vy = gt for free fall in a vacuum. Prove that this is the case. (b) The position of the...
  39. B

    Projectile motion with air resistance

    How do we write differential equations for projectile motion in 2 dimensions featuring air resistance of magnitude kv^2, acting directly opposite to the direction of motion at that moment in time, where v is the velocity in the direction of motion at that moment in time?
  40. I

    What impact does air resistance have on a ball thrown upward with speed x?

    if we throw upward a ball with speed x. What can we say about it when the ball returns in the presence of air resistance? What about in the absence?
  41. D

    Baseball dropped from building with air resistance

    Homework Statement A baseball (radius = 0.0366m, mass = 0.145kg) is dropped from rest at the top of the Empire State Building (height = 1250ft = 381m). Calculate (a) the initial potential energy of the baseball, (b) its final kinetic energy, and (c) the total energy dissipated by the falling...
  42. G

    Projectile motion with air resistance

    Without air resistance, bodies travel in a parabola. What is the curve that is traveled when air resistance is included? I found that there are different air resistances, which curves would these types produce?
  43. I

    Block on incline with air resistance, no friction

    Homework Statement A textbook of mass m = 1.24 kg starts at rest on a frictionless inclined plane (angle  = 30◦). Although there is no friction, suppose there is a drag force (due to air resistance) acting on the book which is proportional to the speed squared and is described by the...
  44. H

    Quadratic air resistance on a ramp

    Homework Statement I kick a puck of mass m up an incline (angle of slope = θ) with intial speed v0. There is no friction between the puck and the incline, but there is air resistance with magnitude f(v) = cv2. Write down and solve Newton's second law for the puck's velocity as a function of...
  45. B

    Dropping objects air resistance

    Homework Statement A creature of mass m and bottom surface area of A is dropped from a height h towards the ground. The creature dies if a force of F_K or greater acts on it. What is the value range of acceleration due to gravity, g, for such creature to survive the fall? Homework...
  46. K

    Air Resistance and Projectile Motion Assignment Task

    1. Hi, I'm currently in my second last year of high school (Australia) and my Physics assessment task is all about cars, however, a stimulus Item is the Movie Speed, long story short, I need to find the minimum angle required, including air resistance at a velocity of 30 m/s. 2. I have tried...
  47. P

    Affect of air resistance on a projectile

    Ok, so I have calculated an ideal speed of a projectile, but now I would like to know how it is affected by air resistance, although I'm only interested in the air resistance when it's outside the barrel, hopefully that'll simplify it a bit. So the formula is: FD = \frac{1}{2}CDρAv2 Can I...
  48. M

    Cycling on the Moon, no air resistance to cause terminal velocity.

    Homework Statement Imagine a cyclist (in spacesuit) cycling on the level on the Moon (so no drag). The external forces acting on them are contact force upwards (from Moon) and weight downwards (from Moon), which balance. Plus an unbalanced friction force forwards (from Moon on the tyres). I...
  49. S

    Deceleration of a projectile (With air resistance)

    Hi there, sorry for asking a question as my first post instead of contributing to the community however I have a problem which I just cannot seem to find an answer to. I am trying to model the flight of a bullet when taking into account air resistance and I am using this equation to get the...
  50. E

    Final velocity with air resistance

    Ok so I am working on this problem and can only get through the first question, the second question keeps stumping me. I have uploaded the question along with my calculations for part a so you can see what I'm doing. ----- A object of mass (m) is shot vertically up with V0 200 m/s...
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