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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At what speed does air drag becomes important?

Imagine an object that wants to move at a speed $v$ trough a fluid. I was thinking that when i ride a bike, there is generally a speed at which air drag becomes a problem, but if i ride slow i does ...
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Is it true that maximum height attained by a body projected vertically upward is irrespective of mass?

For example, if I threw a 1 kg stone and a 100 kg stone vertically upward with the same velocity will they reach the same height, if yes then how?
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Finding a differential equation for a simple model of a meteor entering the atmosphere

Background I am trying to model the position and velocity of a meteor as it enters the Earth's atmosphere. I derived a differential equation (which I plan to solve numerically) to model this in the ...
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Would it be possible to create a perpetual motion machine in an environment without air, friction, or dissipation?

Perpetual motion machines don't work because as it moves, the air molecules hit it and slow it down. Friction slows it down in a similar way. If there were no forces to slow it down, could it work?
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Is terminal velocity applicable in the horizontal plane?

Is there a speed that object A can move at, such that object B would remain 'stuck' to the front of object A, due only to the air pressure as a factor of object A's speed? I realise that friction ...
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How to find the initial value problem for the vertical displacement $x$ of the body? [closed]

A body of mass $m$ falling from rest under gravity experiences air resistance proportional to the square of its velocity. Write down the initial value problem for the vertical displacement $x$ of the ...
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Is atmospheric pressure balanced on an object as it moves?

Consider a box sliding along a friction-less floor at a constant velocity. Now typically atmospheric pressure is 14.7 psi on all surfaces of the object. But if it is moving at a constant velocity, ...
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Is there a drag in a moving fluid due to pressure (reaction) from the walls of the tube?

Consider a tube of linearly varying cross section... Now consider a section of the tube...There are pressure on the ends of this section due to the fluid... Now consider the walls, there is a ...
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How can you model how far a spinning cylinder will move forward during free fall?

I am a high school student and have just started calculus. Part of my project involves doing this experiment where I drop a cylinder from about 10m high with a large backspin and see how far forwards ...
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Theoretical question about velocity and acceleration

Imagine you have a ventilator that is spinning madly an creating strong air up force upwards. Then you put in the middle with a holder a paper ball. Then some-have detach the paper from holder. Sure ...
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How to calculate the precise displacement of an object in projectile motion?

I am curious about how to calculate the precise location of a projectile. Assuming that acceleration due to gravity is $-9.81 \text{ms}^{-2}$, how would you calculate the displacement of a tennis ball ...
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Motion with air resistance [closed]

How to tackle real life problems in KINMEATICS in which air drag in some way is involved? I've attached one such problem in which I was stuck.
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What is the structure on SUV's top back edge? [closed]

I see a lot of SUV's that has the structure as shown in the picture .I am talking about the the top back edge (right above the back window). Wont't it worsen the streamlined design and causing more ...
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How much is a smooth sphere affected by air resistance at different spinning rates?

How to you calculate how much a smooth sphere is affected by air resistance at different spinning rates? None of the answers to How can you calculate air resistances at different speeds? answer my ...
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What is the function for the magnitude of air resistance/drag?

In John Taylor's Classical Mechanics, he gives a basic treatment on air resistance/drag. In order to do this, he models air resistance as $\mathbf{f}=-f(v)\mathbf{\hat{v}}$, and then Taylor expands $f(...
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Is $b$ in the drag force formula $F=-bv$ constant for a certain medium and object?

I heard that $F=-bv$, where $F$ is the drag force, $b$ is the damping coefficient, and $v$ is the velocity of an object, can be used to calculate the drag force exerted on an object moving at a ...
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Work Done By Gravitational Force and Terminal Velocity

Using these two definitions of work: Work = Force * Distance Work = Change in a particle's kinetic energy When a skydiver hits terminal velocity, their change in kinetic energy is basically fixed ...
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How does the width or depth of a container of water affects the speed of an object (e.g. a toy boat) travelling on it?

I am planning to carry out an experiment to investigate how the distance between an object travelling on water (i.e. a toy boat) and the walls would affect its speed. I predict that the speed will ...
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How to calculate the elapsed time while reaching the limit speed?

(Figure drawings belong to me.) In the figure, a person falls freely from the tower at a height of $1500\ m$. When the limit reaches speed, it opens its parachute. By the way, how do we calculate the ...
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Are objects at high speeds subject to friction (in described fashion)?

https://www.youtube.com/watch?v=1NnyVc8r2SM In this video quicksilver moves plastic bullet's with his finger from a different time reference. Needless to say, if bullets were in contact with an ...
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Does weight affect the drag force on a falling parachute?

In my physics class we currently have to do research about a motion and preform an experiment and write an essay on it. The idea I had was to drop two parachutes with different areas from the same ...
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Air drag on a projectile [closed]

A projectile moving through two spatial dimensions has a resolution of two velocities, $$\vec i(V_{0}\cos\theta)+\vec j(V_0\sin\theta -gt)$$ each of which should have their own air drag(?) But also ...
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Non-inertial uniform velocity frame

Suppose, an observer is on a train which has only platform to stand but no walls. The train is moving with a constant velocity with reference to railroad. While moving, the observer feels strong wind ...
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How would the air pressure inside the hyper loop affect the acceleration of the cabin?

I would like to ask a question about hyperloop's inner air pressure, how would air pressure inside the semi-vacuum tube affect the acceleration of the cabin? Is there any functions or equations to ...
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Finding the Initial Launch Velocity of a Ball Whose Launch Angle is Known and Trajectory Contains a Given Point (Accounting for Air Resistance)

I am working on a project that involves launching a ball through a basket (similar to basketball, but on a smaller scale for now). I haven't started building the project yet as I wanted to work out ...
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Object moving against drag: is location equal to $ln(time + c)$? [closed]

I'm creating an asteroids game. For player movement, I want the spaceship to be slowed down as if by a drag force, see e.g. https://en.wikipedia.org/wiki/Drag_(physics), and only the drag force. The ...
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Power required to reach X velocity in X time with drag

I wrote a program that adds force to a car like so: Engine Force = Power / Velocity​ Drag Force = -Velocity²​ Net Force = Engine Force - Drag Force = Power / Velocity - Velocity²​ I'd like to ...
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Free Fall with Drag and Varying Air Density

I am trying to plot a graph in Excel describing a free fall of an iron sphere dropped from an altitude of 12 km, while taking into account the different levels of air density affecting the drag. The ...
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What is meant with overdamped motion?

I'm learning about Brownian motion. I use the approximation of overdamped motion. I read that the average acceleration is $0$ then, but I don't really understand the concept. So, what does overdamped ...
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Optimize crossbow [closed]

I'm currently building a crossbow and was wondering how I might improve the performance of it? I was suggested to fine-tune the rubber band more and maybe change the projectile maybe to a zinc alloy ...
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Velocity of object on extremely low air density?

If we derive velocity in air when setting air resistance to $kv$, we'll get $$v= \frac{mg}{k}\left(1-e^{\frac{kt}{m}}\right) $$ and if air density goes to $0$, $k$ will also goes to $0$. When $t=T$ (...
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Why can you in physics exercises neglect the effect of air drag in case of basketball but not in the case of ping pong ball?

This is not a homework question or anything. I have finished schools and I always wondered why in physics exercises you can neglect the effect of air drag for example in case of basketball and I haven'...
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Does the shape of the pipe (the length not the cross section area) affect resistive force?

Does the shape of the pipe (the length not the cross section area) affect resistive force acting on water? Does keeping the pipe straight or keeping it in curves folded over each other effect the ...
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Stop a car without static friction

If we want to stop a car really fast, we must put on the brakes in a way as to maximize static friction. The brakes create dynamic friction between the axle and the wheel, which in turn creates a ...
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Question about several details in the theory of “Taylor column”

My question refers to a remerkable phenomenon in fluid mechanics, in which flow velocities in a rotating tank of fluid (flow velocity is measured relative to a frame of reference that is rotating ...
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Air Resistance in Taylor Classical Mechanics

In Taylor's Classical Mechanics, he offers up a quick little example to get the reader acquainted with different scenarios in which air resistance approximated as a linear and/or quadratic function is ...
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Terminal velocity of accelerated rain drop

Lets say an airplane flies above a cloud and drops a bomb that detonates inside the cloud. The detonation velocity is 6900m/s. Will a raindrop surrounding the detonation site be accelerated to ...
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PTFE on liquid mercury friction coefficient

Are there any studies or research been done where I could see what is the coefficient of friction on a PTFE plastic sliding on a liquid mercury base? I found that the friction coefficient for PTFE is ...
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Why equations of motion doesn't work here? [closed]

I've been trying to solve a dynamics problem A small projectile is fired vertically downward into a fluid medium with an initial velocity of 60 m/s due to the drag resistance of the fluid the ...
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Distance of a shrapnel ball with air resistance [closed]

How can we determine the distance a steel ball inside a grenade will fly horizontally taking into account air resistance? If we assume that the detonation velocity is 6900m/s(TNT), the ball has a ...
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Drag coefficient in a incline photovoltaic

i want to calculate the drag coefficient of a photovltaic that it's constantly changing angle. Is there a way to measure the Cd in any time? Edit: i want to calculate the Cd to have the Drag of the ...
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Question about a theoretical bee's power to lift

Given a theoretical bee with sufficient (not limited) wing power and material strength of the wing, but with realistic dimensions is it possible for it to lift a human? If not, what are the ...
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Approximation of air resistance of rectangle with angle alpha

my problem is not that hard to explain, but maybe hard to model, because I couldnt find anything appropriate on the forum or internet..;D I need approximate the air resistance force of a rectangle ...
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Vertical motion with linear drag axis problem

I'm learning about linear drag and I have a question with regards to the y component. The y component of the equation of motion (if we measure y downwards) is given by: $$m \dot{v}_y = mg - bv_y$$ ...
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Is the parachute using stall drag to reduce the descent speed?

Is the parachute using stall drag to reduce the descent speed? Because the parachute falls vertically, if we think of the parachute as a wing, then this is a very large angle of attack.
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Sign Problem When Dealing With Quadratic Air Resistance and Gravity [closed]

While dealing with an object falling vertically, and subject to quadratic air resistance, an equation of motion that is often presented is \begin{equation*} m\dot{v} =mg-cv^{2} \end{equation*} In ...
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Is Stokes' law, for drag force in fluids, accurate?

In high school, I was taught that Stokes' law is dependent on assumption that drag force is proportional to velocity, viscosity and radius of the sphere (and the powers/exponents are evaluated using ...
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Deceleration with known drag force

so by no means am I a physicist, but I've been working on a problem where I find that I may be very close to the solution... I'm working on a model roller coaster car that will be slown down by using ...
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How to add drag to a simple pendulum problem function ad hoc?

I recently solved (non-numerically) the differential equation of the simple pendulum problem, $$y''=-c*\sin(y)\tag{1}.$$ I then tried to solve the equation with drag. I failed. I don't want to solve ...
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Defining variable in projectile motion

I'm trying to understand drag on projectile motion but I don't know what this variable $b$ in Eq.1 below on p. 24 in this document is. We define the drag force to be $\mathbf{F}_D$ and the ...

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