Drag Definition and 751 Threads

I am doing a project where in a pedestal fan is alternatively powered using a flywheel. The flywheel is brought to some initial angular velocity by the electric motor. Now, if the power goes off, the fan blades would be coupled to the flywheel and it continues to rotate for the next 10 minutes...

Consider the production of lift only as the reaction force from displacing a mass of air downwards. No matter the mathematical abstraction (Bernoulli, circulation theory) this Newtonian explanation must hold true. So now imagine a rectangular wing in a wind tunnel where the wing spans the...

Was having a breakroom discussion today and I figured I would get an outside opinion. Anywas I have to projectiles/particles flying through the air and are unaffected by gravity. Both have the same drg coefficient, cross-sectional area, air densityetc. The only differences are particle A has...

Hey all, I have been mulling this around in my head for awhile and cannot make sense logically. In thinking about a sphere falling through some random liquid, how does decreasing the diameter of the sphere affect the rate at which it falls? I am thinking of two formulas and the seem to...

Homework Statement a ball makes a free-fall with zero initial velocity and an arrow with 25 m/s initial velocity is thrown to shoot this ball at the same time. The ball is initially h=38 m higher than the arrow. a) Assume no drag force then how long after does this collision occur? At...

For the motion of a spherical ball under water, can its drag force be calculated by knowing only its mass and deceleration?

Homework Statement So the question I've been asked is, that there is a moving car, at time t = 0, moving with a speed of 50 km/h. At t = 0, the car stops accelerating, and thereby slowing down due to two forces: The air resistance drag force A friction which is created by some magnets...

Homework Statement A particle of mass "m" whose motion start with downard velocity V0 in a constant gravitational field. The drag force is quadratic and proportional to kmv2. What is the distance s through which the particle falls in accelerating from v0 to v1. Give your expression for s in...

A) You drag a suitcase of mass 10 kg with a force of F at an angle 48 with respect to the horizontal along a surface with kinetic coefficient of friction 0.32. The acceleration of gravity is 9.8 m/s2 . If the suitcase is moving with constant velocity 2.25 m/s, what is F? Answer in units...

I maintain a small piece of software for the Airsoft/Paintball community. I include some basic energy and velocity calculations but I have also as of a few versions back started including more "theoretical" calculations like how far a BB will travel and that sort of thing. I want to improve the...

Basically, BB ammos were shot from an airsoft gun into a water filled tank. The experiment was recorded using a video camera. I can calculate the approximate instantaneous velocity of the bullet under water at a given time using Logger Pro. 1. Relevant equations Drag force = 0.5 ρAC0v2 2...

Homework Statement A projectile of mass 1300kg is launched from the ground (x =0, y =0) initial velocity components Vx=Vy=108m/s aerodynamic drag force is of magnitude C(V)^2 where C = 0.6 Homework Equations Finding the range and angular momentum initial and final The Attempt...

Would anyone know how to determine the area that a drag shield would have to be to allow an object above not to experience no more then .001 Gs? The drag shield that I was thinking about is just a flat sheet attached to the bottom of the top object by a string. Would this even be possible?

I am trying to estimate the Thrust and Torque generated by a propeller blade by utilising the Blade Element Theory. I was able to get Lift but not Drag. Below is the code generated by Matlab. The calculation procedure is, T1 = twist pitch ratio RTheta = root pitch angle Phi =...

I am trying to estimate the Thrust and Torque generated by a propeller blade by utilising the Blade Element Theory. I was able to get Lift but not Drag. Below is the code generated by Matlab. The calculation procedure is, T1 = twist pitch ratio RTheta = root pitch angle Phi =...

Homework Statement Here, insted of trying to type it out, I will link a picture of the question from the book. Homework Equations The Attempt at a Solution The 3 questions I am having trouble answering are these: 1: How would you plot a graph of the data to obtain a straight line...

Due in an HOUR! Early Physics problem.. relating drag, weight, and speed. Homework Statement A 1.74 m wide, 1.48 m high, 1500 kg car hits a very slick patch of ice while going 21.0 m/s. Air resistance is not negligible. If friction is neglected, how long will it take until the car's speed...

Homework Statement In a simulation of machinery at a mine site, blocks of wood were used as shown in the following experimental set-up in which the two blocks – A and B – both of mass 15 kg are joined by a string over a frictionless pulley. Block A rests on a frictionless incline of 30º...

Can anyone PLEASE help me in pointing me in the right direction? I need to obtain drag coefficient calues for I-beams. I found a site stating it was 2.7, but it says nothing about the orientation?? I basically need the Cd-value for flow parallel to the I-beam, from the top and from the side...

Homework Statement Consider an infinite thin flat plate with a 1m chord at an angle of attack of 10 degrees in a super sonic flow. Describe the angle theta between the Lift and Normal Force, is it the same as the Drag and Axial? Homework Equations L=Ncos(a)-Asin(a) D=Nsin(a)+Acos(a)...

Hello! I have just rediscovered this place since a few years back when I first signed up. This will be my first post, so forgive me if it is a bit long. I have been thinking about this for a while. So I have been thinking about buoyancy. I have learned that the buoyancy force is caused by...

I'm trying to calculate skin friction drag on a truck so I can compare it to pressure drag. I can find the formula and typical coefficients for pressure drag easily enough but I've had a hard time finding it for skin friction. So far I've found this...

What is the expression for Drag Force at very very High Renolds Number flow (>10^6) as we know the expression for drag force between Re1 and Re10^5 = 0.5kpAv^2 but this isn't valid aft 10^5 .. so ...

If a sphere is moving through air. Will it have more drag if it is spinning while moving or just moving ?

I was working on semi-realistic projectile dynamics. The first thing i took was what if a sphere is thrown upwards. g wud act downloads and there wud be drag. Drag=1/2kv^2 (leave k for the moment) (drag depends on v) g=g(R/R+h) (g depends on h) projectile is fired upwards with...

If we consider a sphere oscillates in viscous fluid with frequency w, then sphere has velocity u=u_0*e^{-iwt} In Laudau's book, he defined the velocity of fluid is: v=e^{iwt}*F where F is a vector with only spatial variable involved. The boundary condition then becomes u=v at |x|=R, where R is...

For a physics experiment, I'm testing the drag experienced by floating models with shape, wetted surface, and velocity as the independent variables. I placed the models in a flume tank and connected them to a hanging bucket via a string that passed over a frictionless pulley (see attached...

This occurred to me when I first heard of the Space Time Frame Drag effect, which was confirmed by the results of Gravity Probe B (GP-B). http://science.nasa.gov/science-news/science-at-nasa/2011/04may_epic/" I am not a scientist or a mathematician, so I turn to my fellow humans who are. Do...

I got to thinking about this recently, when thinking about various proposed "renewable energy" systems based on tidal energy capture. Tidal energy is, basically, caused by the interaction of the kinetic energy of rotation of the earth/oceans, the kinetic energy of the moon's orbit, and the...

Hello everyone, i have a question, please help me with equations for magnus force and drag force...i have found an equations for drag force it's, Fd=1/2 * density * v2 * A * Cd . but i can't find equation for magnus force...can anyone tell where i can find it, or if somebody know, let me know...

Given a situation where an object is dropped at a certain height, how should the net force equation be written considering the fact that only gravity and drag acts on it? I'm stuck on whether the equation is written like this: \Sigma F = F_{g} - F_{d} Or like this because g is negative?: \Sigma...

Homework Statement Given a situation where a ball of mass m is dropped off at a height of h, find the equation that would give the velocity of the ball with respect to time given that gravity and drag are intrinsic factors. Homework Equations F_{g} = m g F_{D} = \frac{1}{2}pCAv^2...

hey guys, I am new here and this is my first post, but i need some help. the concept i am trying to explain mathematically is the acceleration a skateboarder (150kg) will have going down a hill (5 degrees bellow the horizontal) completely straight (2 dimensional), including air drag. to make...

Does turbulent flow create more drag due to the exchange of momentum between the slower moving particles and faster moving particles?

Hi I am currently trying to work out the drag coefficient of a car, I know the formulae to work out CD, this being CD=FD/0.5xρv^2A. I can not figure out how to find FD as the formulae for this requires CD. Is there another way to find FD? The information I have is as follows: Car Mass: 1350 kg...

Hi I am currently trying to work out the drag coefficient of a car, I know the formulae to work out CD, this being CD=FD/0.5xρv^2A. I can not figure out how to find FD as the formulae for this requires CD. Is there another way to find FD? The information I have is as follows: Car Mass...

I watch a lot of mythbusters and they constantly talk about the low pressure zone behind a car. I'm confused how does that create drag?

Homework Statement An object of 0.5kg is dropped from rest at an altitude of h=500 meters. It falls while being subjected to a drag force, defined as: fD = 2v . Derive explicitly: v(t), and y(t) and plot v(t) given the initial conditions; use: t between 0 and 0.4 seconds, and v between 0...

Hi everyone, I'm completely new to the aero engineering and have a question regarding drag. The lecturer explained it briefly, threw some formulae at us and now I'm confused trying to make sense of it all. So, i have these two formulae relating to drag: 1) D = 0.5(rho)(V^2)(A)(Cd) and...

The following link is a diagram of the motion of a pendulum I used in an experiment, where L represents the length of the pendulum arm: http://farm3.static.flickr.com/2144/2052427314_f42f4cc193.jpg?v=0 Does drag cause the angle θ to be smaller or larger than it would be with no drag...

Homework Statement On September 8, 2004, the Genesis spacecraft crashed in the Utah desert because its parachute did not open. The 210-kg capsule hit the ground at 311 km/h and penetrated the soil to a depth of 81.0cm . Assuming it to be constant, what was its acceleration (in m/s2 )...

A body falls into viscous liquid which causes the velocity to decrease at the rate proportional to the velocity. v=velocity(m/s) t=time(s) k= constant of proportionality The initial velocity of the body=30m/s k=0.3m/s^2 t=0.25s Solve for v in terms of t and k First step possible...

Homework Statement Now assume that the wind (air) is blowing with velocity va/0 = αi + βj relative to the ground, where α and β are constants. You may find it useful to consider this problem in terms of the velocity of the wind (air) relative to the ground, va/0, the velocity of the projectile...

1. Homework Statement Here's the problem: http://www.flickr.com/photos/38401311@N05/5476715833/ 2. Homework Equations Here are the given equations: http://www.flickr.com/photos/38401311@N05/5477319510/ and http://www.flickr.com/photos/38401311@N05/5477320730/ 3. The Attempt at...

Homework Statement Here's the problem: http://www.flickr.com/photos/38401311@N05/5476715833/Homework Equations Here are the given equations: http://www.flickr.com/photos/38401311@N05/5477319510/ and http://www.flickr.com/photos/38401311@N05/5477320730/ The Attempt at a Solution I really...

Hello everyone, This question isn't exactly a homework problem, but it's a problem I need to solve for my senior project, which is a particle image velocimetry system. I'm running into a nasty differential equation which is what I'm having trouble with. Homework Statement A 30 micron...

so let's say you have two masses attached by a spring in the middle. Also, there is a drag force proportional to the speed, that is F= -bv. I have this problem of writing the equations right. I envision, that I get the masses far apart, so I know there will be force exerted by the spring to...

I guess the Earth's surface pulls around the lower atmosphere with viscous drag effects? What about the upper atmosphere? Does it rotate with a slower absolute tangential velocity? If so, is there any pressure difference that caused by the difference in velocities that would cause any...

I have stuck at a step during derivation. Here it is. D=bv mg-bv=ma a=g-\frac{bv}{m} \frac{dv}{dt}=g-\frac{bv}{m} \frac{dv}{g-\frac{bv}{m}} = dt or, \frac{dv}{\frac{mg-bv}{m}} = dt \frac{dv}{mg-bv} = \frac{dt}{m} let, u=mg-bv \frac{du}{dv}=0-b \frac{du}{dv}=-b multiplying both sides...

I'm trying to obtain the drag force acting on a smooth cylinder at the exit plane of a wind tunnel. I took measurements of pressure at regular degree intervals around the cylinder. The pressure readings are in inches of water, and I know the freestream velocity and the stagnation pressure...