Drag Definition and 713 Threads

Homework Statement A dragster of mass m races another a distance d from a dead stop. Assume a constant instaneous power P for the entire race (provided by engine) and the dragster is like a particle. Find the elapsed time for the race. Homework Equations Well, P = Fv is needed for...

I'm interested in the prehistory of the history of relativity. In this history the nature of light and the ether comes in. One phenomenon that was debated in this context was stellar aberration: that the positions of the stars in the sky change slightly, or, more precisely, the perceived...

What minimum force is required to drag a carton of books across the floor at consant speed if the force is applied at an angle of 45 degrees to the horizontal? Take the mass of the carton 40 kg and the coefficient friction as 0.60. Someone PLEASE help me.. This is what i tried F=ma...

How does one relate the Reynolds number to the Drag Coeffient? It seems the drag coefficient for different velocities must be determined experimentally per set. I know the Reynolds number is a method to determine laminar or turbulent flow, but can it be used to determine the drag coefficient?

I am working on a model of a solar powered drag race. The race: 250 meters, no incline, initial velocity = 0. Classical physics gives us the following equations (ignores aero and rolling drag and wheel rotation): Velocity as a function of time V = (2Pt/M)^.5 P = power, M = mass...

Is there a (freeware?) program to calculate 3D lift and drag for simple flying bodies, e.g. ball, cylinder, cube, wing? There are programs to calculate lift and drag for foils (2D programs), e.g. javafoil of Martin Hepperle. Those programs could be used to study the flow in 2D only. E.g...

Not just a little rocket that goes a 1000 feet in the air, but one that can get into space. How does one take into account that the air density grows less with altitude, etc? Anyone know of any good resources for a problem like this?

A 75.0 kg skydiver can be modeled as a rectangular "box" with dimensions 24.0 cm\times 44.0 cm\times 184 cm. What is his terminal speed if he falls feet first? I know that drag = mg when terminal speed is reached. so drag is 75*9.8 and there's a formula drag = KV^2 where K is drag coeff...

I have a question about a physics problem, this comes from Barger's Classical Mechanics: A boat is slowed by a drag force, F(v) and its velocity decreases according to the formula v=c^2(t-t_{1})^2 where c is a constant and t_{1} is the time at which it stops. Find the force F(v) as a function...

Can anyone Please help me on this. I am totally stuck at this question . thanks... ...A sky diver of mass 80.0 (including parachute) jumps off a plane and begins her descent. Throughout this problem use 9.80 for the magnitude of the acceleration due to gravity. Q1. At the...

If the force of drag is proportional to the velocity, then: F_d = -kv However, the units of k are very strange. Does this mean that the model is completely wrong?

Hello all, I've been having some problems regarding the fall of an object in the vertical direction that has air drag which varies quadratically with speed. The problem is as shown: A gun is fired straight up. Assuming that the air drag on the bullet varies quadratically with speed. Show...

Hello, Does anyone know what is the circulation that gives the minimum induced drag in a biplane? Is it elliptical like a single wing? Thanks

Is air drag proportional to the speed or the speed squared? What data did you gather to support your answer? Can someone please provide me an explanation? Thx.

Just to the point How to calculate Re number? in example for calculating Re number at diffrent points in a boat. How turbulence affect drag? I know simply turbulence will increase the drag but, to what extent; or simply, the formula connecting both. Comparing the drag between turbulence...

i am having trouble calculating various drag co-efficents for a dc -10 in cruise. i have found this data: Thrust: 153000 lb density: 0.00085 slug/ft V= 852ft/s W=580000lb AR= 7.5 e= .8 S= 3958ft^2 Cl= 0.5 I have also found the formulas Cd= D/ (density x S x V^2 /2) Cd= Cdo +...

Average drag?? Hi' this is my first post here:rolleyes: , What is average drag:confused: :rolleyes: (underlined bit) eg, I shot a bullet thru three pieces of plasticene(15cm thickness each) each placed 5 cm apart and the average drag of the plasticene is 5000 N the bullet has a...

A fire helicopter carries a 560-kg bucket at the end of a cable 20.6 m long as in the figure below. As the helicopter flies to a fire at a constant speed of 39.2 m/s ,the cable makes an angle of 39.6 with respect to the vertical. The bucket presents a cross-sectional area of 3.96m^2 in a plane...

It asks to find the vertical force needed to pull the ball in an unknown fluid at a constant velocity. What formulas do I combine and use to find this? They give you the proportionality constant (0.95 kg/s), the constant speed (6cm/s), and the radius of the ball(1.5cm). I already have: F (y...

Is there any relationship (formula) that can determine the force of drag to an object. thanks in advance.

Hi, I have second doubts on air drag problem. Let's say an object is moving with speed v_obj = 15 m/s and that the air is moving with speed v_wind = -2 m/s. What is the the force of air drag? If There would be no wind. The force would be 1/2*drag coeff.*density of air*area*v_obj^2. But...

Hello, I have very interesting physics problem. But i really have no idea how to solve it... Maybe somebody can give me some useful hints? Here we go: "Air drag (air resistance, drag) is a resisitvie force which is the result of a moving object colliding with air molecules. Dervie the drag...

The aerodynamic drag of a new sports car is to be predicted at a speed of 100 km/hr at air temperature of 25oC. Automotive engineers build a ¼ scale model of the car to test in a wind tunnel, where the air temperature is 10oC. A drag balance is used to measure the drag, and the moving belt...

Hello: Need some help here. I am trying to Calculate the viscous drag for a body traveling through water at given velocity and wetted surface area. At this time I am not trying to calculate the pressure drag or wave drag. Basically what I want to know is how many Newtons of force are...

What is the coefficient of drag, Cd, of a tennis ball (roughly d = 6,5 cm, m = 57 g)? Generally; where do I find such coefficients? I'd like to find coefficients for projectiles in water too - since these are supposedly not the same, because of the water viscosity. I've found the "Drag...

Using the suggested algorithm steps of the University Physics extra http://wps.aw.com/wps/media/objects/877/898586/topics/topic01.pdf" I want to make Maple (ver. 10) output values for coordinates, speeds and accelerations (as described in the linked PDF). I've reached the 5th step, which is...

What power must a man expend on a 100-kg log that he is dragging down a hillside at a speed of 0.50 m/s ? The hillside makes an angle of 20 degrees with the horizontal and the coefficient of friction is 0.9 m = 100kg v = 0.50 m/s \theta = 20 degrees \mu = 0.9 From here I thought that...

Is there a way to calculate the pressure drag on objects? without having to turn to CFD software? thanks also has anyone here ever built their own small wind/water tunnels for testing? and how successful they were?

I have been working with projectile motion, and I am just starting to add air friction (drag) into the equations. I've run into a bit of a wall in terms of the calculations, so any help would be appriciated. For a projectile, F(drag)=-c.V^2, where c is a constant (which can be written in...

A 49kg skier leaves the end of a ski-jump ramp with a velocity of 28 m/s directed 22o above the horizantal. Suppose that as a result of air drag the skier returns to the ground with a speed of 17 m/s, landing 10 meters vertically below the ramp. From the launch to the return to the ground, by...

The first part of a pretty involved, 8 part question on modelling drag force states: "A 0.142 kg ball has a terminal speed of 42.5 m/s. If a ball experiences a drag force of R=CV^2, what is the value of the constant, C? I know this is a ridiculusly easy problem, but our text doesn't cover...

I have a question where an 80 kg skier goes down a 40 degree snow slope on wooden skis. The skier is 1.8m tall and .4m wide. I use the drag equation and get 53 m/s. However I am not sure how to add friction into this. Any guidance is appreciated. Oh, friction is .06. I am not looking for an...

This is my first post on this site and I figured I would maybe get a good answer to this question. If the dimples on a golf ball are to reduce the amount of friction due to air resistance, why don't car manufacturers dimple the sheet metal on their cars to reduce coefficient drag?? Just wondering.

There is actually a national association for this. http://www.nedra.com/ The specific energy (Watt-Hrs/kg) of gasoline and hydrogen are quite high (which is why we drive with gasoline) compared to batteries or flywheels which have ~100 times lower specific energy. The specific...

Ok so I have a ball tied to a string hanging. I start a fan and the string now forms an angle. I have heard that there is a relationship between the force on the ball and the wind velocity (obviously) It should be something like F=kv^2 or something like that, what I need to find out is the...

Dear friends, I'd like to know if the meaning of "wave drag" is the same that the resistance of a fluid. best reggards. r. aparicio.

Hello. I'm looking for a drag coefficient of a high molecular PVC material over sea water (fresh or ocean water) I'm designing an electric outboard motor for an inflatable boat I got and was wondering how much ft-lb thrust I would need to go certain speed (~5-10 mph), considering weight (~530...

A boat of mass 250kg is coasting, with its engine in neutral, through the water at speed 3.00m/s when it starts to rain. The rain is falling vertically, and it accumulates in the boat at the rate of 10.0kg/hr. Assume that the boat is subject to a drag force due to water resistance. The drag is...

I'm working on an idea that has to do with placing wind turbines on lake beds to catch the constant undercurrents (not a wholy original idea, I know). One of the most important factors to take into consideration is the lateral force exerted on the tower by the current--which is identical to the...

Some people argue that a non-viscous gas could not result in a drag for moving objects because the kinetic energy could not be dissipated to the gas. However, this view neglects the fact that even if the gas molecules do not interact with each other (i.e. if the gas is inviscid), they still...

I need an equation to solve for the distance traveled of a projectile. The variables that I have are lift coefficient, drag coeficient, launch angle and initial velocity. Could someone please help me find the formula I need. Thank you.

I'm exploring a few topics for my IB extended essay, and since I'm into aviation, my teacher suggested I'd find the coefficient of drag for an airplane. Finding force of net drag would be piece of cake. F_{\Sigma drag}=\frac{Power output}{velocity} According to aerodynamics of an...

During my standing here, I have seen a lot of repetitive threads. But the most recurrent question of every students who post here is about air resistance and drag coefficient. What happens with it?. Is there any hidden mystery we could not see?. This fact is starting to be very unusual and...

Hi Guys, I am doing an extended essay on Terminal Velocity and I need the derivation for the drag force equation: 1/2*C*A*P*v^2 Can you please post the derivation for me? Thanks a lot. Tsering :confused:

Has Fizeau changed the direction of the water in his experiment? If no, wenn we change the direction of the water, is it true that we get twice as much change in fringes? I mean, when we compare the fringes when there are 2 directions of water, is the change more than when we compare one...

Can someone explain me the ether drag hypothesis?

Can anyone tell me the drag of a standard bullet? I realize there are lots of variables affecting this, but what is the ideal amount of drag without considering particulr weather conditions.

I need some help. Our company is holding a paper airplane constest for distance and I've been trying to work out the math to find the best mass, wing-span, wing-chord, launch angle, etc. combination. I've worked through a bunch of the math but I've just been stumped by what appears to be a...

free fall with drag force If the equation F=-bv^2 describes the drag force of an object...then the differential equation for the object's motion would be: dv/dt= -g+bv/m or is it... dv/dt= g-bv/m After solving the equation, should I get... V=mg/b[1-e^(-bt/m)] Also, does this...

drag and time to slow down... and apparent weight. -__- A 1.58 m wide, 1.44 m high, 1300 kg car hits a very slick patch of ice while going 20.0 m/s. Air resistance is not negligible. If friction is neglected, how long will it take until the car's speed drops to 18.0 m/s? Ok drag is...