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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Boat Hull Drag in Shallow Water

I paddle several different types of small craft in the ocean and bays near my home. One phenomenon I've observed is beyond my understanding of drag on a narrow displacement hull. When paddling in ...
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1answer
61 views

What makes the equations of motion dependent on each other?

When Galileo put forward the proposition that the motion of a projectile analyzed into separate horizontal & vertical parts, he made a great contribution to the conceptual basis of mechanics. ...
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1answer
139 views

Drag - Dimensional Analysis / Buckingham Pi

Dimensional Analysis / Buckingham Pi Theorem I'm working on dimensional analysis and I'm having trouble. Here's a problem from my book I'm working on for practice. I'm suppose to consider a small ...
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0answers
28 views

Wind blows to surface, how long legs I need? [closed]

Wind blows onto the surface normally at at speed of 20m/s. The frame (in vertical plane) has two supporting bars in the plane of the ground as shown welded rigidly. What is the length of horizontal ...
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2answers
40 views

Approximating energy loss caused by drag force

We know the usual aerodynamic drag equation is given by: $$F_d = -bv^2$$ Where $b$ here is just some constants combination related to the property of the fluid and the material passing through. My ...
2
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1answer
31 views

Calculating wind force and drag force on a falling object

I'm trying to numerically integrate the motion of an object (say, a falling vertical cylinder). Here, there's a drag force: the wind "acting" on the body (presumably adding horizontal velocity) and ...
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2answers
545 views

Drag force on a flat plate

The solution for this apparently is $\frac{1}{2}C \rho A V^{2}$ where $C$ is the drag coefficient, $A$ is the area and $\rho$ and $V$ are the wind density and velocity. Let's do it without the drag ...
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0answers
19 views

How to calculate wind force (air resistance) on a rectangular object?

Let's say you're driving down the road at 70mph (112 kph). If you hold a sign out of your window that's 20x20 cm square, how much force will be applied to the sign by the relative wind?
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3answers
207 views

Deceleration rate of objects of different mass but the same otherwise

Using a tennis ball as an example object, if one ball weighs 1 ounce and the other is 2 ounces, and both are struck at 100 mph on the same trajectory, would there be any difference in the deceleration ...
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1answer
45 views

Lagrangian formalism application on a particle falling system with air resistance

I have this problem, with a first-step resolution: $$...$$ So, I just don't know why they put the term $\frac{\partial F}{\partial \dot{z}}$ in Euler-Lagrange's equations. Why? I know that the ...
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2answers
54 views

Rocket Altitude Calculation

Assignment Basic data I was launching a rocket model and I tried to calculate the reached altitude. The engine (C6-0) impulse is 10 Ns Total weight is 65,7 g (includes the engine) I calculated ...
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3answers
225 views

Two bodies of equal mass thrown from a height-Practical physics question

I have a doubt about this question: Two bodies of masses $M$ and $m$ are allowed to fall from the same height. If the air resistance be the same for each of the bodies, will the two bodies reach ...
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1answer
26 views

What is total force in this context?

One site said the total forces is the sum of the vectors. My homework question is "A skydiver of mass 90 kg is falling with a terminal speed of 60 ms-1. What does that mean? What is the total force ...
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1answer
39 views

How to find an equation for $x$ in terms of $t$ for a particle falling under gravity with resistance given by $mkv^2$? [closed]

Okay so I have determine the velocity $v$ and displacement $x$ as functions of $t$ for a particle falling under gravity with resistance given by $mkv^2$. I have set up the equation of motion divided ...
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4answers
2k views

How do I calculate the distance a ship will take to stop?

I am a River Pilot and drive ships for a living. These ships are very large and range up to 160,000 Metric Tons. I am trying to figure out how to calculate the distance to stopping. I have a basic ...
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3answers
351 views

Aerodynamics drag of hollow cylinder vs solid cylinder of the same cross area?

I wonder how a hollow cylinder at the same cross area perform vs a solid one, i.e the hollow cylinder has larger radius? I guess they have a similar drag, is that true?
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1answer
66 views

Car Motion: Power and Distance: Air Drag [closed]

I need to workout the amount of Power required by a car, in order to overcome air drag forces. I have figured out that, Power = c(Velocity^3). But, I am unable to understand Power's relation with ...
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0answers
42 views

How to make sure projectile does not go through a wall?

I'm struggling with a problem, in which I want to determine initial condition (initial velocity, and angle) given that I know my ball has to reach (final velocity, location), but I want to make sure ...
0
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1answer
31 views

How to calculate the actual drag force on a wing?

I want to calculate the actual drag force that a NACA 63-412 wing would experience at a given planform area and relative wind speed. Airfoiltools gives a drag coefficient of 0.01676 for the optimal ...
0
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1answer
58 views

Projectile, air resistance and wind

So for my school project I am working on a projectile simulator and air resistance. So I have looked at this. Equations for an object moving linearly but with air resistance taken into account? ...
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2answers
53 views

Working out velocity (including air resistance) [duplicate]

For my computing project, I am creating a projectile simulator but I cant seem to get my head round the air resistance. I tried by working out the horizontal and vertical velocity by solving it ...
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2answers
46 views

Calculate damping constant / coefficient

I am trying to graphically simulate a series of springs in 2D. Now one of the forces I am stuck with calculating is the damping force. The given formula is $F = -k_d v$. I know that $v$ is the ...
0
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1answer
53 views

What forces act on an object submerged in flowing fluid in an enclosed environment (i.e pipe)?

Let's say we have a pipe with water flowing through it and obstacle is inserted into the pipe and is rigidly fixed to the inner wall so that it does not get washed away. What forces are exerted by ...
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0answers
38 views

How velocity progresses over time with a non-constant acceleration? [closed]

A $0.25\text{ kg}$ sphere of radius equal to $0.07\text{ meters}$ is dropped from rest from the top of a building. Granted that it will not hit the ground before, when and after what distance ...
2
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2answers
59 views

Air Drag in orbit

Artificial satellites don't orbit the earth forever. Eventually the Earth's atmosphere, thin as it may be up there, will bring them down. But did you know the linear speed of a satellite in a near ...
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3answers
71 views

Air resistance force [closed]

How do I find the air resistance force and the maximum air resistance force when all I'm given is the mass, terminal velocity, and I know it's falling in quite air? I found a formula online but it ...
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2answers
992 views

Can a simple pendulum be considered a simple harmonic oscillator?

Is the motion of a simple pendulum, a simple harmonic motion? It stops vibrating after sometime.
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1answer
44 views

Why does a parachute open up faster on Mars than on Earth? [closed]

I recently heard that a parachute opens up much faster on Mars than on Earth. Why is that the case? More specifically, during a NASA Edge TV program, one of the scientists working on parachute tests ...
3
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1answer
114 views

What is the force required to move a raindrop?

I'm doing some research on how much force is required to move a typical raindrop (assuming that it is falling straight down) off to the side of X distance. This is for a school project on creating our ...
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1answer
201 views

Equation for Terminal Velocity on an inclined plane and the time it takes to reach it

Now I'm doing a research on the matter similar to this thread : Terminal Velocity of identical shape/size objects which is very self explanatory and very helpful. However in my case, the objects will ...
2
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2answers
78 views

Where does the loss of kinetic energy of the wind flowing over an airfoil go?

When an airfoil is tested in a wind tunnel the speed of the wind behind the airfoil is less than speed of the wind in front of it. That means the wind loses kinetic energy. The reason for that is drag ...
5
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8answers
1k views

Physics Paradox about Newtons Second Law $F=ma$

If force equals mass times acceleration, wouldn't a basketball dropped from the top of the Eiffel tower exert the same force on the ground as a basketball dropped a foot off the ground? They both ...
2
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0answers
55 views

How can we theoretically calculate the number of balloons needed to stop a bullet?

After watching this video, I am interested in proving it mathematically. The problem is that how can we apply the conservation of momentum here to find the velocity of the bullet while we don't know ...
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1answer
68 views

How size of objects lifted by the wind depends on the speed of the wind?

What are the sizes of the objects that could be picked up and flown by tornados, depending on the tornado's speed? To put it another way, assuming turbulent flow and object density much higher than ...
0
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2answers
132 views

A big cannon to match a ballistic missile? [closed]

During the last years of WW2 the Germans used ballistic missiles V-2 (with payload mass ~1,000 kg) to bombard London, from a distance about 300 km away. Suppose the British could respond by building a ...
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3answers
74 views

Reason for motion after terminal velocity

Let some object hang by a string. So no motion since weight was counter balanced no net force. Now string is cut. Object is falling under gravity and experiences air resistance. Terminal velocity is ...
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1answer
102 views

If an object falls - regarding air resistance - does the Potential or Kinetic energy get converted into thermal energy as it is falling?

I read a paragraph on the transfer of potential energy to kinetic energy and heat from this website: Even if air resistance slows down the ball, the potential energy is the same (Mb x g x H). ...
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1answer
56 views

How do I do non constant acceleration questions?

Okay, so there is a type of question that keeps coming up in past papers and I can't seem to crack it. The one I'm doing now is: A skier initially travelling at $50~\text{m/s}$ along a ...
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1answer
48 views

Space and motion

When we throw a ball upwards sitting in a running bus or train it directly comes to our hands but when we do the same sitting on a moving motorcycle the ball falls backwards. Why?
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1answer
88 views

Why doesn't a parachutist, according to Newton, “fall” upwards (because drag is larger than gravity)?

Part of the second law states that an object will accelerate in the direction of the unbalanced force. However, I've been thinking about parachuting and skydiving a bit lately, and I know that when ...
0
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1answer
78 views

Calculate a drag force on a sphere?

Objective Work out a drag force for a unit sphere traveling through air at velocity. Values for formulae are below. The context of this question is that I am calculating this in an atmospheric ...
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2answers
43 views

What are the major differences in group-skydiving as opposed to “single” skydiving?

Surface area/the cross-sectional area is greatly increased, so my thinking is it should decrease terminal velocity as well as a couple of other factors. But mass changes too (since there would be more ...
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2answers
746 views

Why aren't airplanes like golf balls?

Ok this is a silly question but here it goes Although it is good to have a laminar flow of the air around the object for low drag but the laminar flow is prone the phenomena called separation (sounds ...
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2answers
2k views

Which ball falls faster, the cool one or the hot one?

Suppose we're on the top of the Tower of Pisa (or a larger version of it) with two identical cannonballs. We heat one up (say, to 200 degrees Celsius, or some other high temperature before it starts ...
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0answers
25 views

Wind resistance on moving body

Suppose that a vehicle is traveling 60 km/h north, and the wind speed is also 60 km/h going the same direction, would there be wind resistance, and to what extent? Also, if I put my hand outside the ...
4
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2answers
83 views

Reasons for decaying orbit for satellites and spacecrafts

As per newton's law, unless a force is applies, moving objects will continue to move in a straight line. A satellite which speeds at around 17.5k mph would be travelling in a straight line considering ...
2
votes
1answer
77 views

Drag versus centripetal force

I'm trying to see how extensive a gaming engine's physics are. Consider a spinning disc with a box on it which is free to spin around a vertical pole connecting it to the disc. The pole is more ...
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2answers
75 views

How to actually account for air resistance?

What's interested me in my studies thus far is that in a lot of beginner undergrad mathematics and physics courses we're often told to calculate trajectories, velocities, etc. by "ignoring air ...
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2answers
1k views

Will a bullet dropped and a bullet fired from a gun horizontally REALLY hit the ground at the same time when air drag is taken into account?

In a world without air, I understand they definitely would. However, with drag taken into account, I think they wouldn't. Since the drag force varies proportional to the square of speed (ignoring the ...
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2answers
67 views

Will terminal velocity exist on this imaginary planet?

If the atmosphere of an imaginary planet is really thin like 100 particles per cubic centimeter (density of the closest resemblance of vacuum made on Earth) and has mass say, 15 times than that of ...