Drag Definition and 713 Threads

Drag Coefficient out by a factor of 10, can anyone help?? Im doing an experiment on the drag of a sphere and am trying to work out the drag coefficient. From looking at data online this should be around 0.5 (its a smooth sphere). Using a wind tunnel I measured the drag for various sizes of...

Homework Statement Need to solve the differential equation which models the velocity of a sky diver. Homework Equations dv/dt = -9.8 + 0.0045Av^2 where A is cross sectional area (assume 0.75m^2) v(0) = 0 The Attempt at a Solution ok the problem is to find v(t) as a function time. as...

Homework Statement For a touring bicyclist the drag coefficient C(where f of air = 0.5CApv^2) is 1.04, the frontal area A is 0.462 , and the coefficient of rolling friction is 4.60×10−3. The rider has mass 53.0kg, and her bike has mass 11.1kg. Note: p is density of air (1.2kg/m^3) To...

Hi Can anyone explain in detail about drag increase in supersonic speed Why and how drag increases in Blunt shape nose cone to compare with Sharp nose cone at supersonic speed? Ryan

If differential drag on a four cup anemometer causes its rotation, how does one calculate the differential drag on a specific size cup and with a specific wind velocity assuming the wind is constant and in the same horizontal plane as the four cups.?

Homework Statement I want to numerically simulate a fall with air drag. In class, we used these equations to produce a table simulating free fall (using a ti calculator): dt=0.1s a=9.81m/s² tn+1=tn+dt vn+1=vn+a*dt xn+1=xn+vn*dt When I compared that system with the curve produced by the...

This is not a homework problem, just an idea I had. If we have a sphere which is being accelerated in space by a force \vec{F} and we take the drag into account, what would the displacement be after t seconds? If the drag force is \vec{D}=-c_1v-c_2v^2, then the acceleration would be...

Hi i'm writting a report on road vehicle drag. Are there any free resources online / journals that i can use for research? my questions: Relationship between Drag and Turbulence what does a engineer design in a car? (engines, the body-aerodynamics..) and the relationship between...

I have been studying surface tension from my textbook, when I came across a question in which a thin circular plate is placed over water. The surface tension of the water is given. The minimum force required to pull away the circular plate is asked. The dilemma, I am in is in which direction...

Hey guys, I current picked up Fundamentals of Aerodynamics by John D. Anderson Jr. and am having a little bit of trouble understanding some of the equations i am given. This is the first aero book I've picked up so I am not too familiar with aero concepts or terms yet. On page 20...

Trajectory of a bullet with drag In most physics books, they pass over drag problems because of their difficulty. However, I had to do one for a mid-term for a physics class. When the velocity is low (tens of m/s or less), then the drag is proportional to the velocity and the math is quite...

1. Homework Statement Question Details: A "Christmas Tree lighting system is used to start a drag race. The inputs to the system include a start button, a reset button, and two start line sensors. The outputs include lines for Red, Yellow, and Green lights and two Fault lights. When the...

Hello and thanks to all who read this. Recently I've just been messing around with air drag equations, trying to extend applied maths problems to include air drag. And I've hit a road block, at least with regards to my knowledge anyway. I've been using the F_drag = 1/2 P (mass density of...

Homework Statement A speed boat is accelerating at 5 m/s/s. If the Boyant force (the force the prevents the boat from sinking) is 3140 N and the thrust that the motor exerts on the boat is 1876 N, what is the drag on the boat (drag in a fluid is a like friction on land). Homework...

Homework Statement A stone with weight w is thrown vertically upward into the air from ground level with initial speed v0. If a constant force f due to air drag acts on the stone throughout its flight, (a) show that the maximum height reached by the stone is h = \frac{v_0^2}{2g(1+f/w)}...

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.

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...

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...