The force on a body resulting from it's motion through a fluid (gas or liquid). This force is directly opposed to the direction of travel.

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64 views

Effect of air resistance on maximum height of thrown stone

Suppose a stone is thrown upwards from the surface of the Earth in a (very large) vacuum chamber and reaches a maximum height of 1km. If the same stone is thrown upwards at the same velocity outside ...
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0answers
64 views

Projectile motion and drag problem [closed]

I am currently working on an artillery simulation but I came across a problem: I require an equation that will give me the required initial angle when given a velocity the range and elevation, ...
2
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2answers
60 views

How to calculate drag forces on an object

Previously, I theoretically calculated the velocity of a bb, accelerated by air pressure, when it exits a barrel. In short, I calculated my velocity to be about 150m/s. However, I wanted a more ...
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4answers
145 views

Driving on the moon

I think that a car which is applying its max force on Earth stops accelerating (as in, stops increasing in speed) because of air resistance. But on the moon there is none so I think the car would ...
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0answers
124 views

Is drag force on an oscillating sphere an effective model for a swimmer?

I saw the latest video from Sixty Symbols Little Swimmers. At the end of the videos he says that we do not know how to calculate the movement of the little swimmers. He says(6:14-6:40 in video) that ...
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2answers
84 views

Calculate velocity with acceleration caused by drag

Maybe someone can help me with calculating the velocity of a sphere falling down. Initial: Acceleration is $10 ~\rm \mathrm{m/s^2}$. Timestep is $1 ~\rm s$. Approximation of drag = ...
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1answer
147 views

Which formula is correct to find the terminal velocity of a sphere falling through a liquid?

Consider a sphere of radius $R$ & density $\rho_s$, falling through a liquid having density $\rho_l$, attains a constant terminal velocity $V_t$ then in this case the net force acting on the ...
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1answer
53 views

what are the assumptions for the drag force equation to work?

We know that the force of drag $F_{d}=\frac{1}{2}\rho u^{2}C_{D}A$. I can't find a list of the assumptions for it to work. What are the assumptions for it to work?
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1answer
50 views

Drag force and Stokes' force

The drag force equation is, $$F=1/2pAV^2$$ which means that it's proportional to the square of velocity. For Stokes' law, the drag force equation is, $$F=6\pi\mu RV$$ which is proportional to the ...
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2answers
77 views

Calculating speed of satellite in vacuum?

Satellite speed is $35\ \mathrm{km/s}$ after burn for $500\ \mathrm{ sec}$ and after some days or months this speed is reduced automatically $34$, $33$, $32$ respectively. Questions: How the ...
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1answer
46 views

Friction in a fluid

when an object is moving in a fluid(air for example), the air will resist the object's movement: molecules of the air will collide with the surface of the object (no slip condition) and then we will ...
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1answer
27 views

How drag force relates to velocity in the air?

As you know in the formula of drag $$F=0.5 *d*A*C*v^2$$ in different velocities we have different Reynolds number. and the Reynolds number relates to coefficient of drag. my question is how can we ...
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1answer
84 views

How to determine when to decelerate to reach a destination at 0 velocity?

(Sorry, not sure whether this belongs here on the Physics StackExchange or the Math StackExchange.) I'm creating a computer game in which there is a computer-controlled car that needs to travel along ...
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2answers
198 views

Terminal Velocity of 100lb Hail [closed]

In the Apocalypse there is meant to be hail weighing 100 pounds or 45 kg. What would the terminal velocity be, assuming the hailstones are perfect spheres of solid ice? Also, is there a way to guess ...
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2answers
49 views

Does air resistance give a falling skydiver weight?

An observer in free fall is weightless as he is accelerating at 9.8 m/s^2. However, when a skydiver jumps from a high plane, his acceleration gradually slows until becoming 0 m/s^2 at terminal ...
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5answers
965 views

Do objects have a tendency to fall in their most aerodynamic position?

In one of my physics classes, we are using slow motion video to analyze the falling motion of an object and then find out the drag coefficient of that object etc. I noticed while doing this that if I ...
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7answers
3k views

What does an undefined formula in physics mean?

I am trying to figure out how undefined formulas in mathematics relates to physics. Take the following formula for terminal velocity. $$V_\text{terminal} = \sqrt{ mg \over{c \rho A}} $$ Say we have ...
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1answer
38 views

Comparing atmospheric drag in different atmospheres

The book and film The Martian begins with a dust storm on Mars. Is it possible to calculate and compare the effects of a 150mph wind on Mars with winds on Earth? How fast would the wind need to be on ...
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1answer
119 views

A question on Newton's laws of motion [closed]

A force of $50N$ is required to push a car on a level road with constant velocity of $10m/s$. The mass of the car is $500kg$. What force should be applied to make the car accelerate at $1m/s^2$? I ...
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2answers
266 views

Throwing an object with air resistance

say I were to throw a 1 kg ball vertically upwards 100 m/s, with g=10 and also air resistance $0.01v^2$ . By considering the forces I can determine that the speed at which it lands is less than the ...
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0answers
32 views

Clarify throwing an object [closed]

Say I were to throw a 1 kg ball vertically upwards 100 m/s, with g=10 and also air resistance $0.01v^2$. By considering the forces I can determine that the speed at which it lands is less than the ...
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0answers
58 views

Drag Force on a cylinder with its long axis aligned with the flow

yesterday I started looking into equations that link a cylinders diameter $r$ and length $L$ to the force experienced in a highly viscous medium ($Re<<1$). I found the onseen-approximation but ...
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2answers
156 views

Terminal velocity of a sky-diver [closed]

A $75~\text{kg}$ skydiver can be modelled as a rectangular "box," with dimensions $20~\text{cm} \times 40~\text{cm} \times 180~\text{cm}.$ Given the conditions we may use $F_\text{drag}= ...
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1answer
93 views

Whether a large or a small ball fall faster in the air?

Given a ball falling under gravity is subjected to air resistance, after performing a differential to the drag equation, I get: $$g-Z(v^2)/r = a = v',$$ (where $Z$ is a constant.) How can I know ...
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3answers
246 views

Deceleration of a bullet [closed]

Taking into account gravity, air resistance, and wind velocity and direction. (And also temperature if it's actually relevant.) I know the muzzle velocity, the total distance the bullet traveled, its ...
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0answers
30 views

Approximation for rotational drag on a box?

The drag equation gives us an approximation for the drag on an object caused by its velocity in a fluid: $F = \frac{1}{2} \rho A v^2 C_d$ Is there any similar approximation for the rotational drag ...
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1answer
43 views

Maximum displacement of a projectile with $x$ initial velocity and drag resistance

So, as a personal project, I imagined a scenario where a projectile with an initial velocity $x$ is affected by air resistance (drag) but not gravity, and I wanted to find out the distance it would ...
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1answer
157 views

Stokes law in 2-dimensions

Stokes' law states that force on slow moving sphere (i.e. $Re\ll1$) in liquid is $$ F_d = 6 \pi \mu R V $$ In two dimensions we are in trouble (flow around disk in 2d or around cylinder in 3d), ...
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1answer
61 views

How much power is needed to drive two times faster?

Suppose a cyclist riding at speed $v$ decides to accelerate to speed $2v$. Does she have to generate $8$ times more power to sustain that speed? $P_1=F_dv$ If we double the speed, (it usually ...
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1answer
57 views

What is the difference between damping and friction?

What is the difference between damping and friction? Both of them slows down any moving system. So whats the conceptual difference between them?
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2answers
145 views

Lift and drag coefficients on other planets

The question I'm trying to answer seemed simple: how hard would it be to fly on a planet with lower gravity but also thinner atmosphere compared to Earth. If the answer could hint me at how much ...
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1answer
107 views

Air friction at supersonic velocities

I know that if an object moves in the air, it can experience two types of drag, laminar and turbulent. For instance, I have a meteor of ideal spherical shape falling from edge of space, say, 100 km up ...
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1answer
156 views

Free-fall with linear drag

The standard first-course free-fall with linear drag situation posits a particle falling with a constant acceleration (typically due to approximation of gravity), but with a retarding force that is ...
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1answer
75 views

Why is drag neglected while dealing with kinematic problems?

Why is drag neglected while dealing with kinematic problems? While dealing with problems related to finding velocity, acceleration and other kinematic problems, it is mentioned to "neglect drag". ...
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1answer
51 views

Will there be a drag for a solid body already dragged due to reaction?

By learning Fluid Structure Interaction tutorials, I managged to simulate a 2d transient fsi simulation using Comsol fsi fully coupled module. A solid body due to motion in vertical direction ...
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1answer
53 views

Looking at a falling person (vertically) from 60m to the surface, how much wind effect is going to be felt?

I am trying to work out horizontal ranges for a falling person from height (in 10m steps from 0m to 60m). I have used this site http://www.convertalot.com/ballistic_trajectory_calculator.html to ...
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2answers
157 views

Splitting up a force into horizontal and vertical components?

My Bedford and Fowler textbook (4th edition) has a chapter on numerical solutions. I'm having trouble understanding how the textbook splits up the components of force in the $x$ and $y$ directions to ...
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0answers
30 views

How to calculate the thermoelastic energy loss when applying displacing force

I'm trying to calculate the motion of an arrow (or similar shape) in orbit. My understanding has taken me to the following assumptions: There will be drag on the arrow (the drag in low earth orbit ...
2
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2answers
129 views

Why are racing catamarans' hulls not teardrop shaped? [closed]

Looking at the America's Cup 72 class catamarans, I was wondering about their hull shape, which has a sharp wave piercing bow. My question is: since an airfoil shape experiences less drag than a sharp ...
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1answer
631 views

How is the fall time for a parachute affected by the mass of the load?

Why do parachutes with a heavier load fall faster than a parachute with a lighter load?
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2answers
429 views

Why does spinning a golf ball one way make it go further than spinning it the other way?

In golf, you'll often hear people say that one person hits the ball further than another because the one person "draws" the ball while the other "fades" it. I want to know why the direction of ...
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3answers
1k views

Why does a sheet of paper fall slower than the same when rolled into a ball?

It depends on volume but both the sheet and the sphere have the same volume. Does surface area play any role here?
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1answer
59 views

The Real Rocket

Suppose we have a Rocket with initial mass $M_o$ and we want to sent it into space. The equation of motion is (i think... please tell me if there is something i forgot) $$\frac ...
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1answer
207 views

How does height of a parachute affect air resistance compared to circumference or diameter?

I'm trying to find out how much a double in height (making it more ovular or oblong in shape) of the parachute affects air resistance compared to a double in circumference or diameter. Can someone ...
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2answers
1k views

What shape has the highest drag coefficient?

This image from NASA illustrates drag coefficients for several shapes: It is generally accepted that some variation of the teardrop/airfoil shape has the lowest drag coefficient. I was wondering ...
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1answer
99 views

Terminal velocity of a raindrop

I have solved the question and got the answer , but I do not understand why will the raindrop attain a terminal velocity.Without any resistive forces why does it attain a terminal velocity?
0
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1answer
206 views

Would opening a car door at high speed change the path of the car? [closed]

If I were to open a standard, four door, four wheel, car on the highway, would the door swing open and possibly tear off? Would the drag that it creates 'reroute' the car (turn it to the direction of ...
15
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1answer
2k views

Can I move an oil tanker?

Let's say that I'm standing at the edge of a basin made of concrete. This basin is filled with salt water and a ship floats on the water close to the edge of the basin. The ship is neither anchored ...
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1answer
40 views

Why is radiation under Poynting-Robertson drag anisotropic?

According to the Wikipedia article on Poynting-Robertson drag, the reason solar radiation slows an orbiting object is because the re-radiation of photons by the object is anisotropic in the frame of ...
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7answers
4k views

Flat throw vs 45 degree throw of a ball

Why does my sports coach tell me that when I'm fielding I should throw the baseball 'flat' to get the maximum distance? I thought from physics that you get the most distance from throwing at a 45 ...