Drag Definition and 751 Threads

The part that I roughly understand: 1) Drag equation, drag increases by square of velocity, thus if it was only factor to be taken into account then the lower speed the better. 2) In case of cargo ships there is a policy of decreasing speed to reduce fuel usage, called "slow steaming". It...

Homework Statement [/B] A baseball of mass m is thrown straight up with an initial velocity v0. Assuming that the air drag on the ball varies quadratically with speed (f = cv^2), show that the speed varies with height according to the equations. Where x_{0} is the highest point and k = c/m...

Hello, I would like to know how to calculate the drag force per unit length of an infinite cylinder with it's axis parallel to the flow field, I had read about a post here previously titled " Drag force on cylinder in parallel flow" but the slender body approximation is not valid for inifinite...

What is the difference between viscuous force and drag force? Are they the same?

Hi all! How can we know the time and speed of the object before it reachs the terminal veocity, it will reach that, but when? (he's acceleration decreseases right) thanx

Homework Statement Consider two blocks connected by a light, inextensible string over a light pulley as follows: The slope is frictionless and the masses are released from rest. The mass m1 is 3 kg and the mass m2 is 4 kg where m2 is submerged completely (from the beginning) in a liquid of...

Homework Statement A baseball is hit at a height of 3 ft off thte ground. It leaves the bat with an initial speed of 165ft/sec, at an angle of 10 degrees from the horizontal. The linear drag coefficient is k=0.38; gravitational acceleration is 32 ft/sec^2 Homework Equations [/B] Find a vector...

Im currently trying to find out how my book took this drag equation (1/2 CApv^2P) and found the x and y component for accelration (x=(-pACv/2m)*sqrt (v(x)^2+v(y)^2)) &y=(-g-(-pACv/2m)*sqrt (v(x)^2+v(y)^2))

Hi! I'm a bit confused about the source of drag in a 2D flow (actually I'm talking about air). I heard that if the viscosity of a fluid is 0 then there is no drag at all (no pressure and no friction drag). I think I understand why viscosity affects friction drag, but why does it have an effect...

Hello everyone! I was thinking about how to reduce air drag for a vehicle so that one gets better mileage. Here is the definition of the problem: A moving car faces air drag especially at high speed. The resistance of the air layers would try to slow down the car. In order to maintain the same...

I was trying to roughly calculate the energy that could be recovered by regenerative breaking when bringing a vehicle to a stop, so I calculated to total kinetic energy and then tried to calculate the work done by air resistance that would take away from the energy that could be captured. So I...

I'm reading this book on Classical Mechanics and there are two examples in the book where we are asked to find one expression for the velocity $v$, and one for the position $x$, both as functions of time for a particle moving in the x-direction in a "medium" where the drag force is proportional...

Me and a friend at school are doing an honors project for a Computer Science class. We're trying to find the aerodynamic drag coefficient of complicated 3D Shapes entirely virtual. We started out the project with a specific physics engine in mind. It turned out this engine "Bullet Physics"...

I'd like to know how to work out the drag coefficient of a sheet of cardboard. I know the formula, but to get it you need the drag force which in turn needs the drag coefficient. For reference, the cardboard is about 3mm thick and is roughly 60cm by 20cm. It has a 100g weight attached to the...

Hello! I have been trying to make a simulation and it doesn't quite work right, don't exactly know why. I have two questions! 1. Acceleration I have been trying I need a formula that uses. frames till full speed (f) (if framerate is 60fps and this value is 60 then player is at full speed...

So, I was working on some code to handle this. Basically the setup is I have x, y, and z velocity. So if x is negative then move left. If y is positive move up. Z is positive move forward etc. When keys are pressed I add (or subtract) to the proper velocity value. Their are two parts of this...

What helps reduce aerodynamic drag better wheels inside or outside in reference to the above designs? please help.

Hello, What shape has the lowest drag coefficient at ground level and at subsonic speeds (0-150kph) with the following dimensions? Width 60cm (at 45%) Height 120cm (at 45%) Length 220cm These dimensions will fit my motorcycle (not too narrow and not too long). I am thinking it would be a...

Homework Statement a) A fishing boat of mass m moves through water in the +x direction. At time t = 0, it is at location x = 0 and has speed v0 at that precise moment, the boat’s captain turns off the engines and let's the boat drift. Taking the drag force into account, Fd=-Kv^2, calculate the...

I was reading a BBC article about the automotive challenges of building a 300 MPH capable, street-legal vehicle and had a the following thought/question: Could one dissipate enough of the considerable exhaust heat generated by these supercars into the front bumper/air-splitter, so that the air...

Problem 2.14: Explaining the Simplification from Street-Fighting Mathematics by Mahajan "Why is the drag force independent of the gravitational acceleration g and of the cone's mass m (yet the force depends on the cone's shape and size)?"Context Imagine two paper cones formed by taping together...

HI all, I am new to the forum and have a real question for you physics buffs. It has to do with drag. For a mathematics paper, I am exploring the use of physics in accident reconstruction. I want to use calculus to create differential equations for the drag equation .5p(Cd)(A)v^2... I want a...

Homework Statement Hello, Let's say I was given a problem where I have to calculate CD I find everything except CD Now, CD = CD0 + K CL2 I know how to calculate K but I don't know what CD0 is. Would that be a given? or do I have to find it myself? If so, how? Then there's another formula for...

So this problem was a 2 part question. The first part goes as such. 1. A gun is fired straight up. Assuming that the air drag on the bullet varies quadratically with speed, show that the speed varies with height according to the equations: v2 = Ae-2kx - (g/k) (upward motion) v2 = (g/k) -...

In a drag race starting from rest, assume we have constant acceleration and the acceleration is limited by tire friction. I understand we have ##v(t) = at## and I have read elsewhere on this forum that ##a = \mu_sg## where ##\mu_s## is the static friction involved, and ##g## is the acceleration...

Hey everyone, I'm a student working on building a wind tunnel with some classmates. I'm in charge of figuring out the drag and lift force sensors. I'm currently looking these two components: http://www.jameco.com/webapp/wcs/stores/servlet/Product_10001_10001_2128260_-1...

First of all I'd like to apologise for my question, as it will probably be embarrassingly easy to answer but I don't have any idea. I've recently been given the role of running a manufacturing centre for F1 in Schools and everything is going well apart from one area. We have a wind tunnel to...

Homework Statement Flying aircraft X is designed in 2014. The current model has a top speed of 812 m/s, a mass of 72,000 kg when fully loaded, and a maximum thrust to weight ratio of 0.44. Calculate the lifting force and the drag coefficient for the Quinjet when it is flying level at top speed...

Homework Statement Only force acting on body is drag force $$F=kv^a$$ where k is constant, a coefficient bigger than zero and v is velocity. Body is given initial velocity u. Find a such that body travels infinitely large distance.[/B]Homework Equations $$F=kv^a$$ $$F=m(acceleration)$$...

I completed 4a successfully, and with 4b, i have 2 queries: a)why can't I let Reynolds # equal to 2.19 x 10^5 (from part a) then simply sub v=4 instead of 5m/s and rearrange for viscosity? I tried it this way first and got a very wrong answer. Why do we, essentially, need to work backwards to...

Why the 1/2 factor in the equation F_{R} = \frac{1}{2}\rho C_{d}A v^{2}? Why not just divide every C_{d} value found in tables by 2 and omit the 1/2 in the equation instead?

So i am working on a program that models the movement of a rocket through different planets. and i sm starting to get teach my self fluid dynamics. As i was reading a presentation by NASA about the forces that act on a rocket they got into shape effects on drag, i noticed from their equation Cd...

http://scholarcommons.usf.edu/cgi/viewcontent.cgi?article=4836&context=ujmm Ive been awake for thirty six hours and I don't know differential equations. Im trying to find the angle (theta) over the horizontal axis that is needed to hit a target that is 1000 meters away they are basically...

So, I'm currently writing a mathematical analysis of a bullet with a muzzle velocity of 790 m/s. I have found that the standard equation for drag force... Fd = 1/2 * ρ * v2 * Cd * A does not work because the drag coefficient for a bullet (.295) does not account for supersonic speeds. What I...

I have been given the assignment to model the entrance of meteorite in Earth's atmosphere, and ultimately it's impact with earth. The meteorite weighs 0.025kg, and has the speed 28.6km/s 50km vertically above the surface of the earth, giving it a Reynolds number of approximately 3.5*10^7. The...

And how do you find the drag force?

A body moves through a fluid, a retarding force due to turbulence may be experienced. In case of a sphere of radius R moving with speed v through a stationary fluid of density p which it at rest, this force is given by F = kp (R^2) (v^2) k is a constant. Why F is proportional to kp (R^2) (v^2) ?

Hi all. This is my first question on these forums. I am given a task to test out whether or not FD=1/2 CDAρv2 is a good model to test drag force. Where CD is described by Reynold's Number. We have a balloon a small ball and a myriad of basic physics lab equipment.What is a experiment I could...

Homework Statement A 102kg man bungee jumps with a 20ft (~6m) cord (k=167 N). Air resistance is 12N. 1. What should be the minimum height of the platform the man jumps off? 2. What is the maximum velocity he will reach? 3. How high will he bounce up the first time? Homework Equations...

Homework Statement Homework Equations See above photo. The Attempt at a Solution [/B] Hey guys, I'm stuck on this equation never done anything like it but apparently its due to come up on exam next week. Any ideas on where to go with it so far...i stopped as i was about to remove the...

< Moderator Note -- thread moved from General Physics to Homework Help forum > If a ball is projected vertically upwards say with a velocity V. Case 1: Without air drag Case 2: With air drag What will be the difference in v-t graphs and the motion of the ball Air drag D=bv (b is a constant,v...

△Work = △KE + △PE Work = Force x Distance W=F△x Pressure = Force/Area W=PA△x Volume=Area x length W=PV Work = Pressure x Volume KE=(1/2)mv^2 Density = mass/volume mass = density x volume m=DV KE=(1/2)DVv^2 (work done by air pressure?) PE=mgy PE=DVgy (work done by gravity and air pressure??)...

Homework Statement A 710kg car drives at a constant speed of 23m/s . It is subject to a drag force of 500 N. What power is required from the car's engine to drive the car (a) on level ground? (b) up a hill with a slope of 2.0o? Express your answer to two significant figures. Homework Equations...

Homework Statement When Cl = 0.9, find the difference in induced drag for a rectangular wing of 36-ft. span and 6-ft. chord and a tapered wing of the same area, the tapered wing having a 6-ft. chord at the root, the leading and trailing edges being tangent to a circle of 2-ft. radius at the...

1.Small ball with mass m falls from hight h. Find how velocity, acceleration and height depend on time. Air resistance is linear and depends on velocity ##F = kv##. 2. Air resistance ##F=kv## where ##k## is constant. 3. I do not know where to go after ##ma = mg - kv ##.

Hi, I have a raft that move along in a tunnel with the water flow (no propelling engine). A neutrally bouyant cable is attached to the device at the back to supply power for the apparatus on the raft. The cable is about 14mm in diameter and the max length of cable can be 5km. May I ask how can...

How do you calculate how much delta v is lost from gravity and atmospheric drag? I've been looking for days but I can't find anything that actually tells me how it's calculated. For example it takes 1.5 km/s - 2 km/s extra delta v for a low Earth orbit because of drag loss, how was that number...

I'm making a drag racing game. But I'm only 11th grade, and I'm not the best with physics. I won't ask you to make the game, but what formulas to use. I have the following variables(?). From these I have to make a car move realistically :D //Car specs car="2010 Ford Shelby GT500"; //Engine...

I've been trying to figure out this problem for hours my whole group and most of the class is stumped. We understand that we need to relate the equations of F=ma, Fd = (Cd*p*v^2*A)/2, Fnet=Fd-Fg. No data is given. The answer is a V=____ equation. Even just an answer to #1 would be very helpful...

A water skier of mass m is pulled at a constant velocity v by a boat of mass M. Tension in the rope held horizontally by the skier is T. a) Find the total resistive force by the water and air on the skier. b) How much upward force does the water exert on the skier?What equation would I use to...