Drag Definition and 751 Threads

The air drag and magnus pass through spin axis? A ball is flying in the air, and it has spin on y axis, show below. F1 is the air drag force. F2 is the magnus force. My question is: the air drag and the magnus force is pass through the spin axis? Or, the ball will change the torque...

Homework Statement It is said that Lance Armstrong can maintain a average power output of 500 watts for a time trial. The additional power (above that needed to fight gravity) is primarily used to fight aerodynamic drag. On a flat time trial Lance is able to maintain an average speed of about...

Homework Statement You dive straight down into a pool of water. You hit the water with a speed of 6.5 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.)...

Homework Statement You dive straight down into a pool of water. You hit the water with a speed of 7.0m/s, and your mass is 65kg. Assuming a drag force of the form Fd=(-1.40x10^4)v, how long does it take you to reach 2% of your original speed? (Ignore any effects of buoyancy.)Homework Equations...

EDIT***: sorry I figured out how to do this problem and don't need help anymore...:\ Disregard and even delete this thread. Homework Statement A race-car driver buys a car (CAR A) that can accelerate at +5.9 m/s2 . The racer decides to race against another driver with a car (CAR B) that...

Homework Statement You dive straight down into a pool of water. You hit the water with a speed of 7.0m/s, and your mass is 75kg. Assuming a drag force of the form F_D = (−1.00×10^4kg/s)*v, how long does it take you to reach 2% of your original speed? (Ignore any effects of buoyancy.)...

Homework Statement Derive an equation for velocity based on time with drag. Homework Equations The equation is: v(t) = F/b (1 - e^(-bt/m)) The Attempt at a Solution There's some math on paper, but I got down to: F - bv = ma a = dv / dt F - bv = m*dv/dt dt = m*dv / (F -...

How does one evaluate the drag force on a particle moving through a colloid? And how does this depend on the size of the particle compared to the constituents making up the collloid? For particles much larger than the constituents I can imagine one can just do the same as for a normal fluid...

1. a 1400 kg car with a cross section of 1.8m wide and 1.46m high slides across a frictionless surface at 19 m/s. The question is how long does it take (in seconds) to get to 13 m/s? the 2nd part is how long it does it take to get to 10 m/s? 2. D = .5(A)v^2 where A is the area of cross...

Homework Statement You dive straight down into a pool of water. You hit the water with a speed of 6.5 m/s, and your mass is 65 kg. Assuming a drag force of the form F_D=cv=(-1.2*10^4 \tfrac{kg}{s})*v, how long does it take you to reach 2% of your original speed? (Ignore any effects of...

Hi, i want to know what are the real effects of air (drag) in the projectile movement and free fall, i mean how drag or air resistance is calculated in both movements, with equations.

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.)...

Homework Statement A marble of mass m falls through a fluid and is subject to the drag force F=-Av, where v is the velocity of the marble. The marble will reach a terminal speed given by v=(mg)/A. Use dimensional analysis to estimate how long it will take to reach the terminal speed. (Hint...

Homework Statement An object of mass 10kg is projected upwards (from ground level) with initial velocity 60m/s. It hits the ground 8.4 seconds later. Find the drag coefficient, k. Homework Equations dv/dt + rv = -g, where r = k/m The Attempt at a Solution I have used the...

Hello, I'm working on a project about solid fuel rockets and since these are moving through the atmosphere, they experience Air-drag. I'm trying to set up a formula to exactly calculate the height a rocket will achieve. So without the use of any model. The problem I ran into is that I can't...

Hey, I'm having some problems trying to solve the equation for air drag. I'm currently doing a project about solidfuel rockets and air drag is a big deal =) I used this equation for dragforce (Fd) Fd(t)= -0,5 * p * A * Cd (((Fm - Fg - Fd) / m ) *t)^2 which is just a lot of...

Homework Statement http://books.google.com/books?id=qXvESNWrfpUC&pg=PA64&lpg=PA64&dq=%2245-s+freefall%22%2Bskydiver&source=web&ots=RBpsTxCfwb&sig=8uhV4WqEosESfjyP3uyWtn5J7Ys&hl=en&sa=X&oi=book_result&resnum=1&ct=result#PPA64,M1 (P64 Prob2.4) I need to find the equations of motion for a...

In one dimensional cases, will the velocity of a particle tend to the terminal velocity unregardless of any combinations of forces? I try to investigate this equation: mv'+bv=F(t) Using the mathematics theorem at the botton, I found that v --> F(c)/m as t tends to infinity. (where c is some...

Hey guys, If I were to have a large cylindrical building and in front of that building I was to place a smaller square building. Would this reduce the drag on the larger cylindrical building. Here is what I know, just to show that I have tried to understand. Now I understand that the square...

Homework Statement If a ping pong ball is released from rest, how long does it take for the ping pong ball to reach 90% of its terminal velocity? m=2.2g, density(air)=a.29kg/m^3, Cw=.5, diameter=.38mm Homework Equations Fd=1/2*C_{w}+\rho*A*v^2 Newton's second law The Attempt...

Homework Statement A steel sphere in a tank of oil is given an initial velocity v = 2i (m/s) at the origin of the coordinate system shown (if you don't trust the attached image it is essenital). The radius of the sphere is 15 mm. The density of the steel is 8000 kg/m3 and the density of the...

Hi Folks, How would one go about calculating the drag force that would be applied to a wire (or in our case a small (0.130") fiber optic cable, that is inside of a small diameter pipe (.56")? I've tried several methods, but none seem to match what we actually measure when experimenting. We...

hi, newbie needs a little help...what is the formula and could someone please take the time to explain in detail how to compute the elements in the formula for the following task. a submerged styrofoam rectangle with size H 100cm x L 15cm x W 50 cm. the object is submerged at 20 meters (60ft)...

Homework Statement A gun is fired straight up. Assume a quadratic drag force. Show (upward motion) v^2 = Ae^{-2kx} - \frac{g}{k} (downward motion) v^2 = g/k - Be^{2kx} Homework Equations The Attempt at a Solution I can easily solve the integrals unfortunately I am having difficulty setting...

Hi all, I am working on aerodyanmics homework, and I've been stuck on this problem for a while. "The shockwaves on a vehicle in supersonic flight cause a component of drag called supersonic wave drag Dw. Defined the wave-drag coefficient as Cdw = Dw/(qS), where S is a suitable reference...

Hey guys, I'm working on a lab here about pressure variation normal to streamlines. For the last experiment, there is airflow around a cylinder with a static pressure tap. The pressure tap records Cp (divides by dynamic pressure) and angle of rotation. I have data points for Cp vs Theta (10°...

Are there any simple drag experiments (one with limited knowledge in physics and expensive equipment) can conduct? Perhaps one with which involves varying materials.

"Friction's a Drag" t-shirt design Hey all! I'm working on a t-shirt design, and wanted to know what you all thought, and to ask for help as to how to make it better. It's been years since I've done physics, and I could use some help in making a better free-body diagram for the...

So, after looking at all the stuff those geniuses up at NASA came up with, I'm trying to figure out how to get the drag coefficient for the Apollo 13 command module reentry. Heres the stuff I thought were important: Entry-interface 400,000 ft 36,129fps Drogue chutes deploy at...

Sorry if this is a stupid question but can someone give me a quick conceptual overview of what causes drag. I was thinking that it is caused by the object moving through the fluid collides with the fluid particles and by Newton's 3rd law the fluid particles impart a force on the object in...

This past weekend, for fun, I made a pneumatic air cannon, using compressed air to shoot out a small projectile at very high velocity. I'd post my video, but I have not made 15 posts on this forum. What I need to do is find as close as I can to the actual initial velocity of a projectile...

Homework Statement An outfielder throws a baseball with an initial speed of 71.0 mi/h. Just before an infielder catches the ball at the same level, its speed is 85 ft/s. How much of the ball's mechanical energy is dissipated by air drag? (The weight of a baseball is 9 oz.) Answer is asked for...

An engine has 8 cylinders and crankshaft supported by 5 bearings of dimensions Journal diameter = 120mm, Axial length = 114mm, Radiall clearance =0.06mm and Oil density = 890.0kgm^-3. If the engine runs at 900rpm and is lubricated with oil whose kinematic viscosity is 180cSt at cold and...

We are doing a project on the terminal velocity of a badminton shuttlecock and also have to find the drag coefficientof it. The problem that i have is that we are doing this very low budget I.E. throwing the shuttlecock from a window and filming it, now if i am correct to find the Cd we need to...

Is there any experiments I could do to prove that the Drag Coefficient of a Sphere is more or less 0.5 depending on the roughness of the sphere?

For a spinning object does the drag act against the direction the object is rotating?

First off, a thousand apologies if this is in the wrong forum! I have seen the other posts regarding calculating line drag in water for things being towed in water, however, I have the somewhat opposite requirement.. Here is what I know: hydrodynamic object being towed along surface by...

Hi, I am a Senior in High school, looking for some help with a couple of questions that deal with both physics and mathematics. I was given a sheet with 4 scenarios on it, I chose a box falling from a height of 5 meters. The information is shown below: Object mass: 20 grams Dimensions of...

Hey guys, I am working on deriving some equations of motion for an object with air drag. I am using this site to help me: http://www.grc.nasa.gov/WWW/K-12/airplane/flteqs.html Here is my problem, at the bottom of that page they have this equation for horizontal velocity: 1. u =...

Hey, I am trying to calculate the drag force on netting at supersonic speeds. currently I have been using the equation: F = 1/2 (ρ V² Cd A) I am having trouble applying it to netting due to the drag coefficiant, since i cannot find one for netting. Also all the examples I have seen for...

Ok so i have looked and looked for a simple way to under stand how to find drag using the coefficient of drag. the formula i found is off of NASA website and it reads Drag = Coefficient * [ (Density * Velocity ^2)* .5 ] * reference area here is my question what units do i use. When i...

I have a general question concerning the affect of surface treatments or imperfections in the painted surface of the vehicle in relationship to the Drag Coefficient for an automobile. I own a 2006 Hyundai Sonata which has a drag coefficient of 0.32. Over the last six months I have noticed a...

Homework Statement Find an equation describing a body in free-fall in air. This is not really homework. I'm in a differential equations class write now, and I have fun finding real world applications for such things. Homework Equations m\frac{d^{2}y}{dt^{2}} = B\frac{dy}{dt}-mg The Attempt...

I am trying to calculate an acceleratin in a racing (drag)application. I am an engineer at a medical implant manufacturing company so i know a bit about calulations but it has been a while for most (computers,,) Here is the scenario, we race from 150' to 300'. the quickest time determines the...

[SOLVED] very simple drag question Homework Statement A ping pong ball of mass m is thrown downward at twice it's terminal speed. What is its magnitude of acceleration immediately after release in terms of m and any other physical or mathematical constants? Homework Equations This was...

i'm not even sure where to get started with this one because the thorton and marion classical dynamics book is really awful. BEGIN PROBLEM Suppose a baseball, which has a mass of 150 g and a diameter D of 7 cm is released from rest. For a sphere in air, the dynamic drag is F_d=.25 D^2 V^2...

An object is coasting on the horizontal axis, in the positive direction and is subject to a drag force f = -bv - cv^{2}. Write down Newton's 2nd Law and solve for v using separation of variables. So first I wrote out Newton's law as: F= m(dv/dt) = -bv - cv^{2} Solving the integral: dt =...

Homework Statement You have to find the value of k in the drag equation; Fdrag = k*v^2 It is for a car driving. The motors maximal effect is P = 60W, and it uses this, when the car drives 120 km/h or above. Previously, I have calculated that between 30 km/h and 120 km/h, the resulting...

I'd heard this was a relatively newer discovery -- that a blunt-body object traveling through a gas experiences a reduction in drag if that same gas is turned into plasma. I'm haven't read exactly why this occurs, but I'd presume that a gaseous fluid medium becomes easier to pass through if...

First, let me introduce myself. I am new to these forums, but not new to sharing ideas that cause argument. If you think anything I say is wrong, please speak up. The reason I joined was because of this outrageous 2+ year old thread: https://www.physicsforums.com/showthread.php?t=70227 The...