Questions tagged [drag]

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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The dimension analysis for the langevin force [duplicate]

In wikipedia(https://en.wikipedia.org/wiki/Langevin_equation), the langevin force formula is given as $$\langle\eta_i(t)\,\eta_j(t')\rangle = {2\gamma\,k_B\,T\,\delta_{i,j}\,\delta(t-t')}.$$ However, $...
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Would it be correct to state that the damping force and the spring force are equal in the case of critical damping?

(Note: this question is for a spring mass system moving through air) Intuitively it makes sense to me that they would be equal to each other, but I have not found a clear answer referencing the forces....
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Comparing the impact of crash between two objects: Free Fall vs Wind Mill

Object A falls down to the ground directly without any other variable affecting it, which is free fall. Object B falls down to the ground as the same trajectory with object A, while spinning around ...
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A rubber ball gets thrown horizontally from $H$ height find the horizontal distance of the ball till it hits the ground [closed]

There's a rubber ball that has mass $m$, it gets thrown horizontally (from $H>0$ height) with initial velocity of $\vec V(0) = V_0 \hat X$ ($\hat X$ is the axis, meaning horizontal) in addition to ...
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Are drag and lift forces directly proportional to air density?

I'm trying to work out how air density changes displacement during takeoff and up to a height of 35ft. All the websites I find say that the coefficients of lift/drag are Yet I want to know whether I ...
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Wouldn't the cosmic background radiation (CMB) produce drag and thus create a preferential inertial frame?

Because the CMB is everywhere and is isotropic, if an object would have a certain velocity, it could have a pressure differential produced by the CMB which would produce drag till it would stop with ...
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Projectile with air resistance analysis

If a projectile is thrown neglecting air resistance, then the horizontal distance covered by it in ascent and descent is same. if we consider air resistance, then i want to compare horizontal distance ...
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Why does Hoberman sphere open when thrown up? [closed]

Please try and explain this to a dummy :) I haven’t had any university level physics education, at least yet. I was messing around with a mega sphere (Hoberman sphere toy) at a family dinner when I ...
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Would it be possible to ride a bicycle on the surface of Mars?

Could you ride a standard bicycle on the surface of mars? Assumptions: You are wearing a suit to provide life-support You are riding on a prepared smooth flat martian 'road' If you were to ride ...
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Determine the trajectory of a ball on a golf green that is not level

I want to determine the path of a golf ball when someone "puts" from a location on the "green" to the "hole". The distance between the location of the ball and the target/...
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How can I approximate a character's jump in terrestrial circumstances in 2 dimensions?

I'd like to start with the 2-dimensional case to establish simple algorithms for an engine in a simulated environment to approximate physics of a human-sized character jumping long distances with ...
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Kinetic friction and damped harmonic oscillators

I was taught in school that the magnitude of the kinetic frictional force does not depend on the speed. Hence, the equation of motion of the harmonic oscillator in the presence of friction with the ...
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Is the drag force to raindrops at the terminal velocity quadratic or linear?

Air drag is approximated by the following equation $$F=\frac12 \rho A v^2 C_D$$ Depending on the drag coefficient $C_D$, this force may be linear or quadratic with respect to velocity $v$. If $v$ is ...
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Equation of motion with air resistance

If I search for air resistance on a falling object, I find texts stating that it is proportional to the velocity. $$F=mg-kv$$ Is this accurate or approximate? Some texts say that when the speed is ...
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What is the terminal velocity of coin

Very little work has been done at my office for the past few weeks, as we've been bogged down in a debate on the terminal velocity of a coin (the coin in question is a local one, of 9.2g, 28.5mm ...
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Can a bullet return to the starting point (like a boomerang) assuming it is horizontally fired?

Consider a bullet having special aerodynamic shape was fired with a speed of 800 m/s. Is it possible for a bullet to come to the point where it is fired due to its aerodynamic shape. It is assumed ...
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Can a bullet come to the starting point assuming it is horizontally fired? [closed]

Consider a bullet having special aerodynamic shape was fired with a speed of 800 m/s. Is it possible for a bullet to come to the point where it is fired due to its aerodynamic shape. It is assumed ...
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Which forces act on a ball in the air (including air friction) including their equation? [closed]

I am trying to write a ballistic throw simulation with the forces which act on the ball I take into consideration being the gravitational force, and drag. I know that the Magnus effect and another ...
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How fast would a rocket have to go to maintain in the earth orbit without falling down? And how frequent would rocket boosters be needed? [closed]

I was thinking how fast would a rocket have to go to maintain in the in earth orbit? I was thinking of the ISS going 7000kph with rocket boosters every 6 months. What is the most efficient way to ...
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1 answer
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What is the absolute meaning of a drag coefficient of 1.0?

I understand the basic meaning of a drag co-efficient -- the higher it is, the more drag the object experiences when moving through a fluid. I also understand that it's a "dimensionless quantity.&...
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What is the acceleration due to gravity, air resistance and Archimedes' principle on a plane with initial velocity?

So, I am having some fun with doing physics, and I was trying to find the acceleration of a plane moving vertically in mid-air with initial velocity under the influence of: gravity, air resistance, ...
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Terminal velocity of a metal sphere in water

I am trying to figure out the terminal velocity of a metal ball dropped into water or oil. After searching a bit on the internet, I came to the conclusion that I needed to use Stokes' Law and ...
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6 votes
2 answers
747 views

How can I test relative friction at home?

My 7 year old is anxious to test whether or not banana peels are slippery. He has been waiting for 2 years for the science fair to come back. We have the idea to test different types of banana peels (...
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-1 votes
7 answers
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Why does "net force" being zero not mean that the parachuter becomes stationary in the atmosphere?

Take the typical phyiscs / classical mechanics example of a parachuter descending at constant speed. The two forces acting on the parachuter are weight, which has direction towards the ground, and air ...
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What is the optimum Teardrop ratio for Lowest Drag?

Ok, it's well known the teardrop shape provides the least air resistance, minimising drag (note subsonic speeds). But nowhere that I can find is a clear answer of what ratios would provide the most ...
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Transmural pressure versus Perfusion Pressure (driving pressure)

I learnt about 2 types of pressure gradients that needs to be considered in the cardio-vasculature. Transmural pressure (which refers to a pressure gradient felt across the vascular wall, at one ...
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Door Slamming Against Wall

There is a door with length $r$ and mass $m$ hinged on a wall with angle $\theta$, and an equally distributed gust of wind with constant velocity $v$ pushing on that door in the direction normal to ...
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1 answer
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Would a chess board fall faster than the chess pieces?

So if they were both falling in air, would the chess board fall faster since it's heavier?
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What is the terminal speed of a falling object subject to drag proportional to its velocity if it travels a certain distance in a given time? [closed]

This is problem 7.52 from the first volume of Alonso and Finn's Fundamental University Physics. The given data is that a body falls 108 meters in five seconds. We are to find the terminal velocity if ...
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3 votes
1 answer
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Modeling friction with Non-Lipschitz ODEs - Pendulum example

The main objective of this question is to figure out if the following differential equation have [finite-duration] solutions: $$ \ddot{\theta}+0.021\,\operatorname{sgn}(\dot{\theta})\sqrt{|\dot{\theta}...
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Rocket Rotation due to air resistance

I am currently working on a rocket simulation in Python. After the rocket engine stopped firing, the rocket is in free fall. My problem is that I cannot figure out how to calculate the air resistance ...
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1 answer
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Taking drag into consideration, how does mass affect horizontal range given that the impulse applied is always the same? [closed]

If two objects, one light and one heavy but otherwise identical, are given the same impulse from rest and begin to travel horizontally through a resistive fluid, which object makes it farther?
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Projectile flight range in different atmosphere

If we change atmosphere density from 1 atm to 50 atm, how much would cannon's firing range change? Assuming round ball as projectile, 2 km effective range in current atmosphere. There seems to be two ...
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Final velocity and length of a projectile impacting and passing through a target slab?

I want to know the approximate final velocity $v_f$ and length $L_f$ of a projectile that impacts and passes through a slab of given thickness $D$. This is my attempt to solve the problem so far. I ...
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1 vote
2 answers
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Differential equation of the free falling object with air resistance

I'm puzzled by the result I get when I try to solve the differential equation for an object that is falling subject to air resistance. Suppose the $y$-axis is directed upwards, then $\vec{F_a}=bv \hat{...
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1 answer
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Deceleration due to air resistance proportionate to velocity

I'm given a question to suppose that an ice skater on a frictionless surface is attempting to reduce his speed. His initial speed is $v_0$. His deceleration (negative acceleration) is purely due to ...
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1 answer
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Internal resistance for a fluid flowing in pipe

Lets say we have a fluid moving in a pipe with velocity v. what would be the resistance faced by it? in our class, the professor told us that internal resistance faced by fluid is given by R=8nl/pir^...
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5 votes
1 answer
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Is thermal radiation slowing down objects that move relative to each other?

Apparently the CMB is slowing down all objects moving relatively to it. Is the same true for thermal radiation? 1/ Let's have two object with a non-zero temperature that first move towards each other, ...
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Is there an ideal shape for minimizing each type of drag at subsonic, transonic, and supersonic speeds?

The Sears-Haack body minimizes theoretical wave drag in supersonic flow on a body of a given length and volume. Are there shapes that minimize wave drag, viscous drag, turbulent drag, and pressure ...
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Is CMB slowing down all moving objects in the universe?

1/ Object moving relative to the CMB frame of reference will see the CMB blue shifted where it is heading and red shifted where it came from. Correct? 2/ The blue photons ahead should have more ...
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1 vote
3 answers
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How Would a Car Move in Zero-G?

Consider a car floating in a microgravity environment. Assuming the engine can still function (i.e. it is surrounded by normal atmosphere; fuel can still be pumped, etc.), in what ways (if any) will ...
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Is there a difference in energy required to make 2 items with the same exact mass but different material travel the same distance whilst in free fall?

is there a difference in energy required to make 2 items with the same exact mass but different material travel the same distance whilst in free fall? Please answer for all cases of free fall: ...
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1 answer
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Velocity of projectile with both quadratic and constant resistive force

Suppose we have a projectile of mass $m$ that impacts a material with velocity $v_0$. As it travels through the material it is subject to the resistive force $F = \alpha v^2 + \beta$. How can I ...
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5 votes
2 answers
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Fall with drag - ignoring the gravitational force?

Say we have a fall while considering air resistance $$ma=mg-Bv^2.$$ It is a standard differential equation. But then I was asked what would happen, if we ignore the gravitational force $mg$. Now I am ...
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Falling Box Question

Let's say that I drop a 2D box which weighs mass m (lets say 10kg), in an infinitely large 2D space (+ time) which has gravity g (lets say 9.8), constantly pushing the box downwards, the space has ...
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2 votes
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Why don't bullets used in guns have sharp corner edges? [closed]

Why don't bullets used in guns have sharp corner edges? Like why are they spherical or smooth at the tip? Is it to avoid air resistance? But as my sir told that how speed we move proportional we get ...
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Which equation is more suitable when a man lifts his leg in fluid (such as snow, sand or mud), Drag equation or Stokes's law, or other equation? [closed]

When a person lifts his leg in fluid (such as snow, sand or mud), what kind of resistance/viscous force will his leg encounter in the vertical direction, which equation is more suitable? Drag equation ...
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3 votes
2 answers
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At what speed would a wind affect a bullet? [closed]

Firing a gun loaded with the fastest bullet (.220 Swift 1,422m/s or any bullet that is super fast and excellent aero dynamics) in a close range (2cm) from the tip of an air blower. What would be the ...
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1 vote
1 answer
56 views

Terminal velocity of particle in medium with non-uniform velocity

assume that a particle of radius $R_p$ is moving under influence of gravity $g$ in a fluid medium of density $\rho_l$ and viscosity $\mu_l$. then the Stokes settling velocity is given as $$ \mathbf{v}...
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Airplane lift origin and cause? [duplicate]

How does an airplane get a lift? Is it due to the newton's third law or coanda effect or both? I am an amateur in this , kindly use simple terms.😅
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