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. T

    Calculating Friction & Air Resistance for a Train Game

    Hi there, I am new here so please don't be too hard on me yet and move this post if i placed it in the wrong forum. I am developing a little experiment game and i want the train to drive using real physics, but I am really bad at physics. So my question is is how do I calculate the friction of...
  2. O

    How to model a non-linear pendulum with air resistance?

    Homework Statement I have found a differential equation that models a non-linear pendulum with air resistance, and now I have data. I've looked at the following site for guidance on how to analyse the data. It compares the motion of a damped spring, and compares it to the motion of a damped...
  3. O

    Motion of a non-linear pendulum with air resistance

    Homework Statement I need to come up with an equation that would model the motion of a non-linear pendulum with air resistance. [/B]Homework Equations Fc=mgsintheta Fdrag=(1/2)p(v^2)CA The Attempt at a Solution I started with mgsintheta-(1/2)p(v^2)CA=ma After substituting v=r*omega and...
  4. M

    I Physics? Setting up PDE for air resistance at high velocity

    Not sure if this is more appropriate for physics or for differential equations, but this problem centers around an airplane traveling with air resistance. I am not looking to get the most realistic-possible model, as it is just for a video game I am making. Although this is technically a PDE...
  5. C

    Expressing y(t) including the effects of air resistance & gravity

    Homework Statement [/B] Hi everyone! So I've got this similar problem as I posted yesterday, but this one is slightly different due to the presence of gravity: A particle in gravitational field ##~~g## starts traveling upward (positive direction) along the y-axis from ##~~y=0## with the...
  6. C

    Expressing x(t) of a particle (air resistance)

    1. 2D -problem A particle is moving on a frictionless, horizontal surface from ##O_{rigo}## with initial speed ## v_0 ##, as it faces the air resistance force ## F_R ##.2. ## F_R = -mαv ## (where v is a particle velocity) ## \frac {dv}{dt} + αv = 0 ##Show that: ## x(t) = \frac 1 α...
  7. C

    Differential Equation for Projectile Motion with Air Drag

    Hi! I was wondering how I could come up with a differential equation for projectile motion on a 2D plane when air resistance is not negligible. I'm trying to guess the position of a projected ball at a certain time period by approximating the coordinates using the Euler's method. Here, I would...
  8. G

    Air resistance that affects jets and people

    I wanted to ask. Since jets fly at great speed, often even supersonic, I'm curious about next things: 1) What is the relation between air resistance force and energy? 2) How does all that force resistance affect a pilot? 3) What protection do they have, if any? 4) And purely speculative...
  9. C

    Finding the wind-resistance force

    Imagine such situation: There is a sniper who fires his rifle, the bullet travels at the initial speed of, say, 1400 m/s. His target is standing 2000 meters away and the wind is blowing at 30 m/s opposing the bullet's motion. Let's assume that the bullet is fired in a straight lane and it may...
  10. hilbert2

    Insights Damped Motion in Classical and Quantum Mechanics - Comments

    hilbert2 submitted a new PF Insights post Damped Motion in Classical and Quantum Mechanics Continue reading the Original PF Insights Post.
  11. brandon partridge

    How much force would it take to jump on air?

    What i mean is how much force would a person let's say 160lbs have to kick the air it be propelled upwards? This is all based around the double jump idea from games... Air is a gas and gases have resistance so it makes scene if you could put enough force into a spot you should be able to be...
  12. R

    How the angle of launch affect the range?

    Homework Statement I'm about to conduct an experiment about factors that affect the flight of an elastic band. The aim of this experiment is to find how the angle of launch, when shooting a rubber band, affects the range or distance of the shot. Do you suggest to consider the drag force? like...
  13. R

    If air drag is a factor, how will it affect a projectile?

    If air drag is a factor, how will it affect a projectile’s trajectory qualitatively? Its velocity? Its acceleration?
  14. S

    Final velocities with the inclusion of air resistance

    Homework Statement Two rocks are thrown off a cliff at the same initial speed, v. The first rock is launched at an angle, ϴ, directed below the horizontal. The second rock is launched above the horizontal at the same angle. If air resistance is negligible, the rocks would hit the ground at the...
  15. M

    Air Resistance & Upward Velocity: Examining the Relationship

    If air resistance increases with velocity, then if a ball is thrown upwards, does air resistance decrease as the upward velocity of the ball decreases or does it only increase and remains constant when the upward velocity of the ball decreases?
  16. G

    How to Factor Air Resistance into Basketball Trajectory Calculations?

    Hi all, I will be doing an experiment in which I will be rolling a basketball down an elevated ramp. After leaving the ramp, the basketball will free fall for 1.25m before reaching the ground. I was looking to come up with a theoretical trajectory for the motion of the ball, the issue is that I...
  17. A

    Projectile Motion problem involving air resistance

    Homework Statement Ok, so I am attempting to solve a projectile motion problem involving air resistance that requires me to find the total x-distance the projectile traverses before landing again. Given: \\ m=0.7\text{kg} \\ k=0.01 \frac{\text{kg}}{\text{m}} \\ \theta=30 \degree Homework...
  18. M

    Finding the effect of air resistance on period of oscilation

    Homework Statement I'm currently working on the "cavendish" experiment and wish to use/develop a method separate from the casus we've been provided. Now I've nicely calculated and derived everything I need to know, including all the corrections that have to be made for the mass of the rod, the...
  19. A

    What is the velocity of a falling object with air resistance?

    Homework Statement I am trying to develop simulation for a falling object subject to air resistance. Object is similar to Samara seed. object is considered to be under steady vertical descend. know variable : surface area of object (A) weight of object (W) cd: drag coefficient object rotates...
  20. L

    Pendulum in vacuum vs with air resistance

    If a pendulum consisting of a string and a bob is allowed to swing in a vacuum vs in air, which has larger period?
  21. Especial

    Millikan Oil drop lab experiment - equation for speed of drop

    Millikan Oil drop experiment. For my current lab, we are recreating the milian oil drop experiment to measure the charge of an electron. However, we are using 1-micron diameter latex spheres in place of oil drops. Problem: I am having difficulty deriving an equation for the speed of the drop...
  22. Mr Davis 97

    Differential equation for air resistance

    Homework Statement Solve the differential equation ##\displaystyle Cv^2 - mg = m\frac{d^2 y}{dt^2}## Homework EquationsThe Attempt at a Solution The problem is nonlinear, so we need to use unconventional methods. Specifically, if we can express the derivative of y with respect to v, then we...
  23. Clara Chung

    Free falling with air resistance question

    Homework Statement An object falls under gravity and air resistance force bv. It is known there is a characteristic time τ=m/b such that the object comes close to the terminal velocity for t>>τ. Derive an exact expression for the distance d traveled at time t. Homework Equations not sure...
  24. N

    I What is the maximum height reached by an object with air resistance?

    Hello everyone, I was playing around with some equations regarding air resistance. I tried to calculate the height that is reached by an object that is projected vertically into the air. However something seems to go wrong when integrating. Starting with the equation of motion \begin{align*}...
  25. J

    How to account for air resistance?

    All the physics classes I've ever had modled object motion as though it where in a vaccuum, becuase air resistance is obviously a pain in the but to account for. Mathmatically how would i account for it? Say after one second of free fall how much of my velocity would be lost due to air? Im...
  26. A

    Motion under influence of a resistive force

    Consider the 1d motion of a body under the influence of the force given by F = -m*γ*vα. m is mass, γ is a constant of appropriate dimension, v is velocity and α is dimensionless constant. The value of α for which the motion will come to a stop in finite time is to be calculated. I solved the...
  27. D

    Do Rubber Band Propelled Planes Fly Further?

    Hello PF! I have a project/competition in freshman college Aerospace that calls for a plane that can stay in the air for as long a time as possible while going as far as possible. The requirements don't explicitly say we need rubber bands as a propulsion but pretty much prohibit everything but...
  28. M

    Would this work to decrease air resistance in sports cars?

    Okay so here is my idea, not really sure how well (if at all) it would work but I am wondering if it would be possible (assuming battery technology is good enough) to ionise air in front of a formula 1 car (or plane or whatever) giving it a charge (like the way lightning works) , then creating...
  29. Ryaners

    Using Python to calculate projectile motion with resistance

    I'm trying to write a program to calculate the trajectory of a projectile with air resistance. I've made the following function which calculates the position of the particle based on a given launch angle and initial velocity: def traj_fr(angle, v0): #function that computes...
  30. B

    How does air resistance affect a ball's acceleration?

    Homework Statement A ball is thrown vertically upward with an initial speed of v0. It experiences a force of air resistance. The positive direction for all vector quantities is upward. Does the magnitude of the acceleration of the ball increase, decrease, or remain the same as the ball moves...
  31. J

    How does air resistance affect terminal velocity for a diver?

    Homework Statement Homework Equations F=ma The Attempt at a Solution As the diver's velocity increases, then force F due to air resistance would increase, so D is out. And C is out too, as air resistance would be equal to its weight at terminal velocity. The answer is B, but how do we know...
  32. J

    Experiment to Investigate Air Resistance

    Homework Statement I collected data for an experiment involving air resistance. We made paper disks and timed how long they took to fall over a fixed distance. We changed the radius of the disk. We found that as you increase the radius they take longer to fall. I am trying to explain my results...
  33. B

    A feather and a ball falling with air resistance

    Homework Statement Suppose you drop a feather and a steel ball of equal masses (0.014 kg) at the same time from a height of 2.2 m and you are told that the feather hits the floor 3.5 s after the steel ball. Estimate the value of the terminal velocity of the feather in air. Then, estimate the...
  34. N

    What is the Terminal Velocity of a Skydiver with Given Parameters?

    Homework Statement I attached a screen shot of the problem. Homework Equations D= 1/2 C p A v^2 bv=mg The Attempt at a Solution I spent 3 long hours on this problem. I confused myself even more. Please help me understand what is going on.
  35. N

    If we neglect air resistance, then the range of a ball

    Homework Statement If we neglect air resistance, then the range of a ball (or any projectile) shot at an angle θ with respect to the x-axis and with an initial velocity v0, is given by R(θ)=v_0^2/g sin(2θ) for 0 ≤ θ ≤ π/2 where g is the acceleration due to gravity (9.8 meters per second per...
  36. Z

    Projectile with Air resistance problem

    Homework Statement The resistance to motion of a projectile, of mass m, is proportional to its speed. When falling vertically its terminal velocity is 19.6 m/s. The projectile is thrown vertically upwards with gravity acting downwards. (a) Assume that the resistance to motion can be expressed...
  37. Q

    Is air resistance dependent on mass?

    Is air resistance dependent on mass? thanks!
  38. J

    Which is the air resistance formula?

    I'm trying to solve this ecuation: Y_1=(-m)/2k((T-mg-kv^2)/(T-mg)) I'm having some truble at finding a correct formula to find the air resistance. In my research through Internet I found loads of different formulas but I don't exactly know which is the correct one. In an other discussion on this...
  39. E

    Impact of air resistance at varying angles

    I recently read that the impact of air resistance on the horizontal range increases as the launch angle increases (http://moodle.davidson.edu/moodle2/pluginfile.php/121168/mod_resource/content/2/Brancozio%20fly-ball%20paper.pdf). A graph depicting this is attached. Is there a reason for why this...
  40. P

    Question on velocity changes in free fall

    Homework Statement Assume a ping pong of mass 3g is falling, and it has fallen 1m and is now traveling at 5 m/s. If the air resistance force is half its weight, how far will it travel in the next 0.1 seconds. [Hint: you may want to sketch a velocity-time graph) Homework Equations Understanding...
  41. tswanson4444

    Calculating drag coefficient for complex shape

    Me and a friend at school are doing an honors project for a Computer Science class. We're trying to find the aerodynamic drag coefficient of complicated 3D Shapes entirely virtual. We started out the project with a specific physics engine in mind. It turned out this engine "Bullet Physics"...
  42. M

    Projectile motion with air resistance

    Homework Statement This is a standard projectile motion problem, the mass is m, the drag is F_r = - alpha *v, where alpha is a positive retarding coefficient. The origin is the ground and at time t = 0 the horizontal and vertical velocities are positive a) Write down Newton's second law for...
  43. V

    Projectile Motion/ Air Resistance Question

    I actually have 2 questions that I am getting stuck on around the same point.. Question 1) An arrow with a mass of 80g is fired at an angle of 30 degrees to the horizontal. It strikes a target located 5 m above the firing point and impacts the target traveling at a speed of 20 meters/sec. If...
  44. B

    Calculating baseball pitch speed

    My brothers and I want to calculate our pitch speed. We have a simplified formula: M = (D/T) x (3,600/5,280). This will obviously have a large margin of error, but we'll try our best to accommodate. I need to know how to calculate air resistance into the equation. Thanks!
  45. K

    Conservation of Energy - Max height WITH Air resistance

    Homework Statement A ball (m=0.7kg) is dropped from a height (h=30m). The air resistance force is given by the formula F=kv^2 where k=0.0228 and v is the ball's speed. The ball bounces after a perfectly elastic collision. Calculate the maximum height the ball reaches after the collision...
  46. Y

    Modeling Quadratic Air Resistance in 2-D using Mathematica

    Homework Statement I am working on a little project in which I analyze a video I found online and try to determine if it is real of a hoax. The video I am analyzing includes a man throwing a football off of a football stadium (at the very top) and making it into a basketball hoop at field...
  47. H

    Conservation of Energy: work done by air resistance on rock

    Homework Statement A 250 gram rock is thrown with a speed of 30.0 m/s. It has a speed of 22.5 m/s just before it strikes the ground. Determine the work done by air resistance. There is also a diagram which yields more information. The rocks path is horizontal and it strikes the corner of a...
  48. P

    How can I incorporate wind resistance into my projectile motion calculations?

    Homework Statement I'm currently in computer programming class, and I've finished a project and want to improve on it. We had to figure out how to calculate the gravitational acceleration and time traveled of a projectile to hit a target. I'd like to add horizontal variables in my code, like...
  49. Ineedhelp809

    Calculating the Impact Speed of a Bullet Fired Straight Up

    Homework Statement A bullet fired straight upwards experiences an acceleration due to air resistance of 1m/s2 during its entire flight. If it leaves the barrel of the gun at 300m/s, with what speed does it hit the ground? Homework Equations None given The Attempt at a Solution integral of a=t...
  50. P

    Air resistance when moving in the same direction but faster

    Hi all, So after the wind almost blew me off my bike today, something occurred to me. It goes like this: We all know that if we bike in the same direction as the air does, then we will get a little push and it makes our journey easier. Then suppose we get a little adventurous (reckless people...
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