What is Drag: Definition and 747 Discussions

Homework Statement We sink ball with density 1450 kg/m^3 in some liquid with density 1400 kg/m^3 a) What's acceleration in moment we drop the ball? b) With what constant speed will the ball sink in balace? Assuming that the drag force is linear. Radius of ball is 3mm and viscosity of...

I am having problems showing the following: ##f## and ##g## are two linearly independent functions in ##E## and ##\theta : \mathbb{R} \to \mathbb{R}## is an additive map such that ##\theta(\mu \nu) = \theta(\mu)\nu +\mu \theta(\nu); \mu,\nu \in \mathbb{R}##. Show that the function; ##\psi...

Homework Statement So, I'm building a "Monkey Gun" and I want to be able to find the instantaneous velocity of my dart at a certain time. I shoot the gun at some angle, θ. The problem is, if I divide the velocity into x and y components, each depends on and impacts the other (the force from...

Homework Statement A car moving with speed v is subject to a drag force F_{d}=0.5\rho A c_{d}v^{2}, where \rho is the density of air (1.25 kg/m^{3} at STP), A is the cross sectional area of the car, and c_{d} is the drag coefficient. A Honda Civic has A=1.9 m^{2} and c_{d}=0.36. Assuming...

I really need help with this question. A small floating object initially moves with velocity v on the surface of a liquid at latitude λ. The drag force due to liquid is F=-αv. Find the shape of the trajectory of the object due to drag and Coriolis forces. What will be the trajectory if α=0 ?

How does momentum and inertia affect changes in speed, when considering acceleration from thrust, or from decelleration from drag? Say, for a fixed mass of 100kg, at a velocity of 10m/s, is a force of 10N is applied in the forwards direction, then F = ma -> a = F/m. a = 10/100, a = 0.1 m/s^2...

My friend and I are working on a realistic FPS sniper simulator and we wanted to be able to realistically model things like bullet drop, flight time, and impact energy. I've managed to find the drag coefficients for different rounds and I know the exit velocity, so now I want to use that to...

In the game ArmA 2 they try to simulate ballistics and have some kind of drag model. I would like to try to find out how it works. I collected the following data from a bullet fired from a rifle in the game. Initial Velocity: 900 m/s Time of flight: 0.000 sec 100m Velocity: 819 m/s...

Homework Statement A stubborn, 100.0kg mule sits down and refuses to move. To drag the mule to the barn, the exasperated farmer ties a rope around the mule and pulls with his maximum force of 826.0N. The coefficients of friction between the mule and the ground are s=0.800 and k=0.220. What...

Homework Statement Part (iv) The Attempt at a Solution My attempt is below. Is it correct ? Homework Statement

Can we assume that the coefficient of drag of a car model is constant using one of the values from: http://en.wikipedia.org/wiki/Drag_coefficient The reason I ask this is because the coefficient of drag of a car varies with velocity. So wouldn't it change depending on how fast the car is...

Homework Statement A solid sphere - 20mm in diameter, σ (specific gravity) = 1.3 dropped in water μ=1*10^-3 and ρ=1000 determine the terminal velocity for the sphere. (hint- guess the value for the drag coefficient then iterate) Homework Equations Fd=(1/2)*Cd*ρ*(U^2)*A...

A television transmitting antenna is placed on top of a mast which is 30m high and 300mm in diameter. The mast is on top of a tall building. The wind blows at 35m/s and at normal atmospheric pressure (1.225kg/m^3). If the drag coefficient for the mast is 0.2. calculate: (i) the total drag...

1. A bird is gliding at an angle of 15° to the horizontal at a constant velocity. If the mass of the bird is 0.45 kg, calculate the lift and drag forces acting on the bird. 2.A bird is gliding with a constant velocity. Its forward speed is 5 m/s and its sinking speed is 0.88 m/s. If the...

How would a strain gage be set up (on top of the model? around the sting?) to measure drag? I don't quite understand the connection between the force of drag and some sort of compression/tension force...? Thanks for the clarification.

As far as I understand, a spaceship going around rotating black hole should gain additional acceleration due to frame drag. Right? So, would there be max speed gain, like in gravity assist, or could you accelerate infinitely? Thanks.

Hi, I'm a bit confused by induced drag on an aerofoil and hoping somebody can clear it up for me. I understand that as air slips around the edges of the wing due to the pressure differential between the top and the bottom surfaces, the angle of attack at the ends of the wings is...

Hey guys, I am back again with a drag related question, earlier I posted a thread asking how I could incorporate wind into a drag equation of sorts to create a 3d graph that shows the trajectory of a projectile. The help I received helped me add head winds and tail winds, however I am now...

Hey guys, I'm new to these forums so I am unsure if this is the right place to be posting this, but here it goes. I have been working on a drag spread sheet using OpenOffice Calc to predict where a potato will land when fired from a potato gun. I have gotten pretty far along, using...

(this is all in context to a java 2d object and is not homework related) I have an object with velocity v and position x. Its acceleration is directly proportional to velocity squared ie a=k v^{2}. Given the objects initial velocity u and its initial position x_{0} how would i work out its...

So I'm writing a Scientific Lab Inquiry (college research lab write up), and my professor pointed out a major error in my assumption of air/mathematics but I can't for the life of me figure out what is wrong or how to fix it. Attached is a copy of the paper in all it's glory/infamy. There's a...

A softball having a mass of 0.250 kg is pitched at 99.6 km/hr. By the time it reaches the plate, it may have slowed by 10.8 percent. Neglecting gravity, estimate the average force of air resistance during a pitch, if the distance between the plate and the pitcher is 15.2 m. F=ma...

Hello! I have some questions about the drag equation and aerodynamics: F = \frac{1}{2}ρv^2CA I'm trying to calculate the atmospheric drag on a streamlined body (the drag coefficient will be a very small number) with a velocity of about 8 km/s at about 38,000 meters altitude, where the...

i couducted an experiment trying to calculate the drag of a toy car going down a slope, i measured this at different distances 2.0m to 0.5m at 0.1m intervals along a 15° slope. i measured the time using light gates. i put one light gate at the end of the slope and one where the car started from...

How can I find the drag and lift force such as below illustration? http://s4.postimage.org/sxmnflttp/dragillustration.png Below is my calculation: http://s4.postimage.org/ao75d6r0d/dragcalculation.png

1. A 940 kg motorboat accelerates away from a dock at 2.2 m/s2. Its propeller provides a thrust force of 3.9 kN. What is the drag force exerted by the water on the boat? 2. I know that the force can be get by F= m a 3. My teacher told us to draw a free body diagram to get all the forces acting...

Homework Statement Hi. I'm not a student, and I'm old, so I don't remember physics class in high school. So I apologize for my question. I'm trying to figure out how you would translate aerodynamic drag to someone like me- a layman. I have a wing on my car that, if I were to tilt it to...

We know that the drag force on an object is defined as: FD = ρ*v2*CD*A/2 , where ρ is the density of the fluid the object is traveling in, v is the velocity of the object, CD is the drag coefficient of the object and A is the surface area of the object. Rearranging the formula to find drag...

While writing a physics report, I obtained a data that for balls of rough surfaces, there is a higher drag force and thus the ball can stay stable at a much smaller angle when put up in an airstream. However, while analyzing this result, I found out that the drag coefficient is not always...

I have an idea that I would like to discuss. My idea is to emit a low pressure low friction gas out the nose of a small arms bullet. I believe it would lower the drag over the body of the bullet thus increasing velocity and range. I just need to know if the phyics are right is this...

http://en.wikipedia.org/wiki/Tsiolkovsky_rocket_equation ideal rocket equation. No fudge for atmospheric drag. how much is it a factor?

Hello, I understood that in low velocities the standrad drag equation: F_d=\frac{ρv^2C_dA}{2} Could linearized to something like: F_d=γv I am looking for the drag coefficient(either γ or Cd) for either a prolate or a tri-axial ellipsoid at low velocities (less than 0.5 m/s) in water. I found...

Homework Statement The drag force experienced by the spherical pebble in water is given by: (0.5)CpwAv2 mass of pebble = 83.8g radius of pebble = 2 cm C = 0.7 (a) Write down the differential equation governing pebble's descent. (done) (b) Derive an expression for terminal...

Homework Statement What is the difference between the two proportionality constants for liner drag F=b*v and quadratic drag F=k*v^2 considering a general object moving trough air? i know that k is given by 1/2*ρ*C_w*A where C_w is the drag coefficient

Homework Statement the forces will be like this m⋅dv/dt=-m⋅g-k⋅v I need to find the velocity equation and the place equation, thereby meaning the integral of the velocity equation. for the condition t,v=0,v_0 The Attempt at a Solution i have found this...

Homework Statement I am having trouble deriving the velocity equation for an objekt moving vertically upwards. the net force will be m*dv/dt=-mg-kv^2 where k is the drag. At the time t=0 the object's velocity wil be v(0)=v_0

Homework Statement I am having some trouble deriving this velocity equation. I the net force will be [itеx] m * dv/dt = - mg - kv^2 [/itеx] Because the object is moving upwards. At the time t=0 the velocity will be [itеx]v(0)=v_0[/itеx] Homework Equations The Attempt at a Solution

came across the concept of Frame dragging. i cannot find if this phenomena also aids in addition to the conversation of angular momentum the formation of an accretion disk around neutron stars/black holes. cheers

If a moving vehicle (van) had a 10cm diameter aperture in the bodywork at the front, which forms the mouth of a sealed container within the vehicle, would the drag experienced by the vehicle increase in proportion to the size of the sealed container? In other words, would it matter if the sealed...

Homework Statement So for my intro engineering class one homework problem is given as follows. "Considering only aerodynamic drag force, calculate the maximum speed (in mph), that a vehicle would experience with the following specifications." Horsepower = 330 Mass density of fluid = .077...

Homework Statement I am trying to find the velocity of a car as it is going down hill. I have the final velocity which is 11.2 m/s and the initial velocity which is 2.23m/s. I have to include Air drag to get my velocity. I also know that there was 21,456 J of energy lost from up the hill to...

I understand a little about eddy currents and synchrotron radiation; I believe I am correct in saying that they are examples of energy loss (essentially drag) when moving though a gradient of magnetic flux. But are there any materials/effects/things that cause drag when moving through a uniform...

Homework Statement A water droplet starts falling from rest from a height h and a quires the terminal speed just before reaching the ground. If g(acceleration due to gravity) is assumed to be constant and the radius of the drop is r, find the work done by air drag. The density of air is...

Calculate the density at which the available thrust of a jet propelled aeroplane is equal to the minimum drag for the full fuel load case. Use the simplest assumption for the variation of engine thrust with density. Wing area, S = 29.5 Weight, W = 88000 CD,0 = 0.02 k = 0.044 Max thrust...

I am new to the forums and need help with something. I have been using a spreadsheet that somebody else made in order to help me design an electric motorcycle. I have been inputing my own data using most of his calculations and I have noticed that he did not calculate any aerodynamic parameters...

I'm carrying on a research project in my school about roller coasters and I'm wondering if the following question is right. I have a drag force which equation is \frac{1}{2}\rho·v^{2}·C_{D}·A where \rho is air density; v^{2} is squared velocity, C_{D} is drag coeficient and A is effective area...

Hello I am preparing for my aerodynamics exam and I'm having trouble with this question. Why is the Reynolds number of the airflow over a wing important in determining the value of lift and dragThe Reynolds number is important for determining laminar and turbulent flows over a body. It is a...

Hi all, I´m a researcher in computational biology thinking on topics quite far from my field. Would you help me? Thanks in advance! I want to calculate the drag force in air of big rigid spherical and cylindrical objects at speeds form 0 to 100 Km/h. Their diameter would range from 1 to 20m...

Homework Statement From dimensional analysis it is found that the drag force F that a fluid (density ρ, viscosity μ) exerts on a sphere (diameter d) moving through a fluid at a velocity u is given by cD = f(Re), where . The table below gives the relationship between the drag...

Homework Statement Consider a flat plate moving at V = 105 ft/s in an atmosphere with P = 2100 psf and T = 75F, with a viscosity of vis = 3.7373e-7 slug/ft-s. The plate has a 2 foot chord and a 3.5 foot span. a. Find the drag on the plate for: i. A boundary layer that is laminar over the...