What is Drag forces: Definition and 11 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. S

    Using Newton's Laws: Friction, Circular Motion, Drag Forces

    Here is my attempt at setting up the equation: I set up the equation to find the acceleration of the box: F-Ffr= m*a after finding the acceleration, I can use the acceleration and plug it in the formula v^2=(v0)^2+2*a(x-x0), which will get me the value of (x-x0)The solution sheet says that F...
  2. Anachronist

    Intuitively, which of these coroplast fins has less drag?

    Here's a crude model rocket fin made out of a material called Coroplast (corrugated plastic): And here's the exact same fin with the flutes cut out from all around the edges, allowing the edges to be squeezed shut and sealed with tape: It may look like there are small openings, but...
  3. tomdodd4598

    I What is a "Blunt Form Factor"?

    Hi there - a very simple question. On Wikipedia, it is stated that for the drag equation to be accurate, "the objects must have a blunt form factor and the fluid must have a large enough Reynolds number to produce turbulence behind the object". My question is what is a 'blunt form factor'? I...
  4. W

    How Does a Skydiver's Velocity Change with Distance After Parachute Deployment?

    Homework Statement A sky driver reaches his terminal velocity of 373 ms^-1 and deploys his parachute at a height of 1500m, the drag force =bv^2 and weigh can be ignored. Find an expression for velocity as a function of distance traveled from the point the parachute was deployed The Attempt at...
  5. wirefree

    Is differentiation a possible approach?

    Question: I have a function of time. Its expression has a constant 'b' in it. I am asked to ascertain how changing 'b' affects the function. Specifically, I have velocity as a function of time which accounts for drag forces; 'b' is the drag coefficient. I am asked to ascertain how changing 'b'...
  6. I

    Help With Lift And Drag Forces On A Ball, Bernoullis Principles.

    Homework Statement Any help would be appreciated, whether that is formulas or working out. Questions For each of the vertical levitation examples calculate the lift force exerted on the ball. For each of the inclined levitation examples calculate the lift and drag forces exerted on the ball...
  7. S

    Points of action for thrust and drag forces and lift-drag ratio

    Hi, Can anyone help explaining the points of action of drag and thrust forces on an aeroplane in flight and also the realtionship between Lift-Drag ration and wing configuration?! Any help would be great!
  8. M

    Understanding the Concept of Reference Area in Drag Force Calculations

    How much force does air resistance have on a freefalling object on Earth? No equations, please.
  9. W

    What are the differences between regimes I and II in drag forces?

    So I was looking at MIT iTunes U physics videos, and the professor talked about regimes I and II in the video about drag forces. I think regime I has to do with the temperature of the medium and regime II has to do with the density. But, I cannot find that information in my 1st semester physics...
  10. S

    Drag forces on someone diving into a pool

    Homework Statement You dive straight down into a pool of water. You hit the water with a speed of 7.0 m/s, and your mass is 75 kg. Assuming a drag force of the form FD= (−1.00×104 kg/s)v, how long does it take you to reach 2% of your original speed? (Ignore any effects of buoyancy.)...
  11. S

    Calculating Drag Forces on Arcs for Engineering Project

    I'm currently working on an engineering project for my high school engineering course, and the knowledge of physics I should have for this project is more than I actually know. I want to build a catapult that can shoot a tennis ball at an 8” target on the ground from 30 feet away. I want to take...
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