Drag Definition and 713 Threads

I working on a new airfoil design. Please tell me the airfoil having highest lift to drag ratio, I need it for comparison.

"A two-dimensional structure is tested in a wind tunnel with an air density of 1 kg/m3. The wind tunnel is 1 m high, with upstream and downstream pressures of 1.5 kPa gage (i.e. above atmospheric) and 1 kPa gage respectively. If the mean velocity of the entering air is 30 m/s and the downstream...

F = -kv2 A fishing boat of mass m moves through the water in the +x direction. At time = 0 and x=0 it shuts its engines off and begins to drift. It experiences drag according to the above equation, calculate the boat's speed as a function of time. I've tried taking F = ma so a = -kv2/m...

Homework Statement How large is the mass of sweat (water) evaporated by a man with 80 kg body weight assuming that his body temperature decreased due to the evaporation by 1 °C? (Assume, that the human body consists mostly of water and the heat of evaporation of water at body temperature (37...

x’’(t)=g-Fd/m=(9.81metres/sec^2)-(k/m)(x’(t)) where x''(t)=du/dt and x'(t)=u=dx/dt I enter this at http://www.wolframalpha.com/input/?i= and I get the solution x(t)= -(c1me^(-kt/m))/k+c2+9.81(m/k)t But x(t=0)=0 x’(t=0)=0 x(t=0)=c1+c2 x’(t=0)=c1-c2 =>c1=c2=0 =>x(t)=9.81(m/k)t and this...

Homework Statement The problem is Kibble & Berkshire 3.8, http://books.google.com/books?id=0a8dk0eDxgEC&lpg=PP1&ots=DT80qg1JSM&dq=kibble%20berkshire&pg=PA68#v=onepage&q&f=false" is a link. (The problem is on page 68. Equation 3.17, referred to in the problem, is on page 53.) I figured out the...

Homework Statement A golf ball and a basketball are both moving through the air at 10 m/s. Which has the higher drag coefficient? a. The golf ball's drag coefficient is much higher. b. The basketball's drag coefficient is much higher. c. Both drag coefficients are about the same...

Knowing the weight, the mass and the acceleration of the object, how can I find the drag force? I used the following formula --- "Weight – drag force = ma" --- but I'm not sure whether it is right or wrong. Mass = 0.14 Weight = 1.34 Acceleration = 8.63 1.34 – drag force = 0.14 x 8.63...

MAJOR EDIT: I fixed my position integral and got the answer to 1.ii) Homework Statement A parachutist jumps from a helicopter that's not moving. The mass of the person is 80kg, the quadratic drag is f = -Cv^2 where C = 3,52. Neglect the Earth's rotation effect. The parachute is opened as soon...

Homework Statement to qualify for a race a car must achieve an average speed of 254 km/hr on a track 1600 meters long. if a car covers half the track with an average speed of 227.5 km/hr what minimum average speed must it have the second half to qualify? Homework Equations...

Hi First ever post on Physics Forum. N2: F=ma can be written as dv/dx=-gy-(bv/m) g=grav. constant b=constant where D(total drag force opposing dir. of...

Homework Statement What is the drag force on a 1.6 m wide, 1.4 m high car traveling at 30 m/s (approx 65 mph)? Homework Equations drag force=.5*p*v^2*coefficient of drag*A The Attempt at a Solution density of air depends on temp but that's not given so I used a density of 1.2...

Hello PF'ers, I'm having a bit of conceptual trouble with understanding the drag force derivation. I take the drag force as being D \ = \ \frac{1}{4} \ A \ v^2 . I want to imagine dropping an object from the highest point at which the equation w = mg will be a satisfactory...

Homework Statement A block of mass m slides on a horizontal surface that's been lubricated with a heavy oil so that the block suffers a viscous resistance that varies as the 3/2 power of the speed. If the initial speed of the block is Vo at x=o, show that the block cannot travel further...

http://www.grc.nasa.gov/WWW/BGH/reynolds.html (Reynolds Number)=(Inertial Forces)/(Viscous Forces) My question is: Force of drag Fd=? Wild guess: Fd=Inertial Forces?

I was wondering; Imagine two situations: 1) I rotate an axle with a strong magnet attached within a conductive coil (a dynamo). 2) I rotate an axle with a strong magnet attached without a conductive coil. Does the presence of a coil (and therefore the generation of current in the coil)...

Homework Statement A ball of mass 0.5 kg traveling horizontally through the air with speed v(t) experiences a drag force DT (t) whose magnitude is given by: DT (t ) = 0.01[v (t )] 2 The speed of the ball is found to reduce from 10 m/s to 8 m/s over a time interval t, during which time...

Homework Statement I'm trying to crudely approximately the distance individual masonry units fly when a blast load impacts a masonry wall. I'm a structures guy so I can calculate when the wall will failure, but I am having trouble with the calculus associated with the equation of motion. My...

A golf ball without dimples experiences more drag because the deflection area of the airflow around the ball is larger which means that the pressure drop behind the golf ball is also higher. The increased drop in pressure creates a suction vacuum behind the golf ball which pulls it back and...

1. Homework Statement The small scale drawing given in the Annexure shows the general arrangement and dimensional data on an early version of the English Electric “Canberra” B.1 bomber, powered by two Rolls Royce “Avon” jet engines. It was and is an extremely successful aircraft, designed by W...

Homework Statement The small scale drawing given in the Annexure shows the general arrangement and dimensional data on an early version of the English Electric “Canberra” B.1 bomber, powered by two Rolls Royce “Avon” jet engines. It was and is an extremely successful aircraft, designed by W E...

Hello all, I recently made some model rockets and thought it would be fun to predict their height before setting them off this weekend. I thought it would also be interesting to compare the difference in the predictions of a model with no drag and a model with quadratic drag. Surprisingly...

Okay, thanks Hikaru and K2 for your help on the accelerated drag problem. Now I have another drag related problem I wonder if you you help me with. Say a car is put in a wind tunnel and is measured to have the following attributes: Frontal Area: Ax Side Area (Right): Ay Frontal Coefficient of...

I've been doing some research on sphere aerodynamics, in particular that of soccer balls, and was wondering if there was any way to separately calculate the pressure / form drag, and also the surface / viscous / skin drag. I know that Stoke's Law of F=6(pi)RnVc, where R is the radius of the...

What is the drag force on a 1.6 m wide, 1.4 high car traveling at A) 10 m/s B) 30 m/s I'm getting 68 N for part a and 615 N for part B using equation D=.25pAv^2 P= density of air (1.22 kg/m^3) and A is cross sectional area of obect as it faces the wind). *I plugged in 1.22 for p...

What is the terminal speed of a 75 kg man that jumps out of a plane feet first? The man can be thought of as a rectangular box with dimensions 20 cm * 40 cm * 1.8 m I tried equation v terminal = sq rt (4mg/p* area). P=1.22 I used . 72 as Area. That's wrong. Help please! I calculated...

I am a bit confused by the equations for Fdrag (the force drag applies to an object) and Pdrag (the power required to overcome drag). F_{drag} = \frac{1}{2} C_{d} \times \rho \times A \times \nu^{2} Where: C_{d} is the Drag Coeffecient (a dimensionless, empirically-derived constant)...

Hey folks, New to the forum and eager to tap the resources of all your brilliant minds. Here's the problem. I'm modeling a system as a cylinder rotating on its end. Under a dynamic equilibrium situation with an applied force of a known value, I know its angular acceleration and...

Profile Drag and Pressure Drag? Can someone please tell me the difference between profile drag and pressure drag if there is one??.

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

Pretty simple question: Is it possible to completely calculate Lift and Drag from the pressure distribution over an airfoil? Atm, I have Lift worked out as well as the Induced drag ( correct me if I'm wrong. ) but am having trouble working out how it would be possible to get the skin...

Hi, I'm looking for a correlation of the drag force on a cylinder in parallel creeping (stokes') flow (i.e. the flow is alongside the axis of the cylinder). My length-to-width ratio is such that assuming an infinitely long cylinder is perfectly okay. Does anyone know where I can find such a...

Calculate velocity of the skydiver of mass M= 80kg as a function of time. The air drag coefficient D= 100g/m = 0.1kg/m. Assume that the skydiver has v=o at t=0. In my book high speed air drag is f=Dv^2. I found Vt= 88.5 m/s with Sqrt(mg/D). BUT this is not the V they are asking for :(...

Hello, I'm a french student. I will have to present a project for an entrance examination in a year's time and I've chosen to work on swimsuit. (is it considered as howework ?) The problem is that I find most of the information on english written websites, which makes it hard to understand...

Homework Statement A car starts at 100 m/s and deploys a parachute. After 10 seconds its speed decreases to 45.45 m/s. Calculate the distance the car has traveled in this duration. The effects of ground resistance are ignored. drag coefficient and planform area product (Cd * A) = 4 m^2...

Overall the sum of the forces of drag on an object must of course be negative. But is it possible to have areas of an object that contribute to negative drag? I have the pressure distribution over a NACA 0015 (symmetrical aerofoil about x-axis) at many angles of attack and I need to calculate...

Homework Statement This isn't exactly homework, but this seemed like the right place for this question. I'm working on an add-on for Orbiter - the space flight simulator - and would like to be able to determine the equation of motion for an object traveling at an initial velocity (v0), with a...

hello! i want to calculate th total drag (surface and pressure drags) for my prototype car, a project of shell eco marathon. Actually our prototype has the shape of an airfoil, its quite stream line.the Cd we use is 0.04 which is used for streamline shapes. ihave calculated the pressure drag...

Homework Statement Suppose a very light ball is thrown at a wall. The wall may be thought of as an xy-plane. At the moment the ball hits the wall, does it have 0 velocity in the x, y and z directions? Is drag on the ball (in each respective direction) small enough to be ignored at...

by how much will single-slotted Fowler-type flaps increase the drag coefficient of an aerofoil?

Homework Statement Consider an object that is coasting horizontally (positive x direction) subject to a drag force f = -bv - cv^2 . Write down Newton's second law for this object and solve for v by separating variables. Sketc the behaviour of v as a function of t. Explain the time dependence...

Induced drag of an airfoil should be inversely proportional to velocity^2 wiki states "Since induced drag is inversely proportional to the square of the airspeed" Ok but [Induced Drag = 0.5 * Density * Velocity2 * Wing Area * Induced Drag Coefficient] which is proportional to the veloicty^2 and...

Approximetly how much is the drag coefficient if orginally the coefficient is 0.02689. I know it depends on aircraft etc but I am only looking a rough estimate.

Homework Statement Droplets in a deodorant spray have mass of about (4x10^-12) kg and a radius of about 0.1mm. Estimate the terminal velocity of the droplets in Air of Viscosity (2x10^-5)Nsm^-2. Homework Equations Stoke's Law, F = 6pi rvu where r = radius, v = velocity and u = viscosity...

What are the effects of Spacetime "Drag"? I have learned that general relativity predicts that a rotating body (such as earth) produces not only a curve in the spacetime continuum, but it also 'drags' spacetime in the direction of rotation. 1) How is this possible? 2) What effects does...

Homework Statement Hi everybody, I'm new in the forum, I've been reading some post but couldn't find the information that i need. I'm making a game of soccer in 2d, and i need to calculate this: I have a basic physics simulation, and when a player has the ball i need to found the force...

I am teaching 7th grade Science. We are doing the shoe drag lab. To start we drag a shoe across the floor with a rubber band. Then we add a rock to the shoe and drag it again, measuring the stretch of the rubber band with a ruler. My question is: by adding a rock to the shoe, are we adding...

Do you guys know where I can buy some dummy parts and boards that I can practice drag soldering with? I would like to give it a try, but I don't want to ruin expensive working components.

I have been trying to find lift and drag coefficients in terms of pressure. So far I have found multiple equations. Below is what I have found after multiple research on the web. I am using these equations in LabVIEW. My input is going to be upper and lower surface pressure and I have to find cl...

Homework Statement A yacht is of length 5m and travels at 10m/s. A scale model of length 0.5m is tested in a tank in order to predict drag on the yacht. Assuming that the fluid density and viscosity are the same for the yacht and model, can we obtain similarity? What is our best value for...