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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16
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6answers
3k views

Does a person inside a falling bus fall to the front of it?

So I was watching Final Destination 5 and something caught my attention. There's a part where a bridge collapses and everything falls apart, so there's this bus that has a person inside (unaware of ...
1
vote
0answers
29 views

Question about Elon Musk's Hyperloop Suspension [on hold]

So one of the proposed suspension systems that will be used on the hyperloop include the externally pressurised air cushions. These cushions lift (or atleast help lift) the capsule and reduce drag ...
2
votes
1answer
31 views

Is motion along the $x$ and $y$ axises independent with quadratic drag?

It's often stated that motion in the $x$ and $y$ axises are independent, so that changing the $x$-velocity will not influence changes in the $y$-velocity. To me it seems that with quadratic drag (drag ...
2
votes
1answer
166 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 ...
1
vote
1answer
43 views

How to calculate distance travelled while car is rolling, given start and end speed?

I'm trying to calculate the distance travelled by my Formula Student racecar if it starts at a certain speed, goes into Neutral (no acceleration, no brakes, just rolling on its wheels), and ends at ...
3
votes
3answers
5k views

Which will stop first a heavier car or a lighter car?

If the friction from brakes, wind resistance and all such factors remain constant, which will stop first? A heavier car or a lighter car? How will the momentum of the car and gravitational pull on a ...
1
vote
1answer
31 views

How much does air resistance affect the angular velocity of a golf ball?

I'm modeling the flight trajectory of a golf ball, and using angular velocity to calculate the Magnus force. Currently, I'm assuming angular velocity to be fixed throughout the ball's flight. How ...
0
votes
2answers
33 views

Find the force needed to accelerate body to a certain velocity for a certain time with respect to drag force

So, the problem is straightworward when we suggest that air resistance force is constant: $$ \vec F = \frac {\vec V_1 - \vec V_0} {t} m / b $$ $$ \vec V_0, \vec V_1 - \text {initial and final ...
0
votes
4answers
7k views

Why does a parachute decrease terminal velocity?

Terminal Velocity depends on two things- surface area and speed. These are inversely proportionate. If both these variables affect terminal velocity, why do parachutes slow you down? Initially you ...
0
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0answers
22 views

A simple detailed book on how/why model rocket engines and parachutes work

I'm planning on getting a model rocket in the near future to fire off w/ my 2 daughters (9 and 11). I'm going to require first that they learn how/why rocket engines and parachutes work (so they can ...
0
votes
0answers
21 views

Measurement of drag (?) tension between two surfaces

I want to know if there are (reasonably inexpensive) devices to measure the tension between two surfaces. Beware of my terminology: the first help I need is to actually formulate my question ...
1
vote
3answers
459 views

Forces on an aircraft - thrust, lift, drag, weight

I'm extremely sceptical about the wikipedia page on aircraft flight mechanics. When describing 'straight climbing flight', it says: lift is unable to alter the aircraft's potential energy or ...
1
vote
1answer
71 views

Could one fire a bullet with sufficient speed to leave the Earth?

Consider a gun or rifle fired directly upwards. My original question was what speed would be required to escape the Earth. The escape velocity from the surface of the Earth is the classic $$v_e = ...
3
votes
3answers
257 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 ...
0
votes
2answers
23 views

Friction drag force

When an object moves through air, the air closest to the object’s surface is dragged along with it, pulling or rubbing at the air that it passes. This rubbing exerts a force on the object opposite to ...
0
votes
1answer
97 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? ...
2
votes
2answers
231 views

Do wind turbines convert the kinetic energy of air?

It is often said that wind turbines convert the kinetic energy of the wind into electricity. But in respect to horizontal wind turbines with airfoil shaped blades this is imho not the case. Wind ...
0
votes
3answers
41 views

Velocity and transfer of energy for a body in free fall

I just need to check if my understanding of the transfer of gravitational potential energy to kinetic energy is correct. Is anything wrong below? Say if a body were suspended at a height h above the ...
0
votes
1answer
79 views

Which point in the graph does a parachute open?

The diagram represents speed-time for a sky diver. He falls freely from an aircraft then opens a parachute and later lands safely on the ground. At which point did the parachute fully open? ...
-1
votes
2answers
68 views

Free-Falling Object

How does the presence of air affect the rate at which a body falls? What is the rule for falling objects, when there is little or no air resistance?
2
votes
2answers
57 views

Mathematics of simplified air resistance

I recently encountered a problem in which when throwing a ball upwards one has to determine whether it goes up or comes down faster when not only was gravity to be considered, but also air resistance ...
0
votes
0answers
22 views

Drag coefficient of a rectangular prism

How do you find the drag coefficient, specifically for a rectangular prism-shaped body? What other factors must be taken into consideration when calculating this value?
6
votes
1answer
2k views

Drag on a spinning ball in fluid

I am a physics newbie (high school level) and I am wondering what happens when a spherical object is spinning on the spot in a bunch of gas (no gravity here, just an imaginary physics sandbox). Am I ...
1
vote
0answers
45 views

The behaviour that saves more energy/ petrol when driving down-up-hill [closed]

This question is in a way a follow-up of this one: Can a car get better mileage driving over hills?, it is similar to that, is no engineering question and is in no way a homework problem, I'd like you ...
0
votes
4answers
194 views

What is the friction force at terminal velocity?

As terminal velocity is inversely proportional to viscosity or fluid friction, then my question is: at terminal velocity, the fluid friction is maximum or zero?
2
votes
1answer
74 views

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 ...
0
votes
1answer
75 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. ...
0
votes
2answers
71 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
votes
1answer
83 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 ...
0
votes
2answers
739 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 ...
0
votes
0answers
53 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?
1
vote
1answer
57 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 ...
0
votes
2answers
139 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 ...
1
vote
3answers
244 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 ...
0
votes
1answer
29 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 ...
0
votes
1answer
43 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 ...
11
votes
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 ...
0
votes
3answers
402 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?
0
votes
1answer
103 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 ...
0
votes
0answers
52 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
votes
1answer
54 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 ...
1
vote
2answers
73 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 ...
1
vote
2answers
70 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
votes
1answer
82 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 ...
1
vote
0answers
44 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
votes
2answers
70 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 ...
-1
votes
3answers
84 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 ...
1
vote
2answers
1k 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.
0
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1answer
52 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
votes
1answer
118 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 ...