What is Terminal velocity: Definition and 223 Discussions

Terminal velocity is the maximum velocity (speed) attainable by an object as it falls through a fluid (air is the most common example). It occurs when the sum of the drag force (Fd) and the buoyancy is equal to the downward force of gravity (FG) acting on the object. Since the net force on the object is zero, the object has zero acceleration.In fluid dynamics, an object is moving at its terminal velocity if its speed is constant due to the restraining force exerted by the fluid through which it is moving.As the speed of an object increases, so does the drag force acting on it, which also depends on the substance it is passing through (for example air or water). At some speed, the drag or force of resistance will equal the gravitational pull on the object (buoyancy is considered below). At this point the object stops accelerating and continues falling at a constant speed called the terminal velocity (also called settling velocity). An object moving downward faster than the terminal velocity (for example because it was thrown downwards, it fell from a thinner part of the atmosphere, or it changed shape) will slow down until it reaches the terminal velocity. Drag depends on the projected area, here, the object's cross-section or silhouette in a horizontal plane. An object with a large projected area relative to its mass, such as a parachute, has a lower terminal velocity than one with a small projected area relative to its mass, such as a dart. In general, for the same shape and material, the terminal velocity of an object increases with size. This is because the downward force (weight) is proportional to the cube of the linear dimension, but the air resistance is approximately proportional to the cross-section area which increases only as the square of the linear dimension. For very small objects such as dust and mist, the terminal velocity is easily overcome by convection currents which prevent them from reaching the ground and hence they stay suspended in the air for indefinite periods. Air pollution and fog are examples of convection currents.

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  1. L

    Finding the terminal velocity of a model rocket from a list of velocities

    Ok, i have some rocket data from a 20,000 foot launch. I have the times, altitudes, and velocity at said time. Is it possible to find the terminal velocity from this long list of numbers? I tried graphing the velocities to see where the curve flattens out, since usually that is where terminal...
  2. Victor Correa

    I Terminal Velocity proportional to the Drag Force 𝑚𝛾𝑣² in free fall

    Can anyone help me? I know that's wrong, but i don't know where. Thanks for your attention so far.
  3. Y

    B Terminal Velocity Equation in vertical cylinder with some fluid

    I just have a question that could you guys make an equation that expresses the terminal velocity based on followed condition? - When diameter increase, velocity decrease - velocity should change depending on both cylinder and sphere's diameter - We know every variable - The sphere is in...
  4. OscarF

    Physics Homework Question on terminal velocity and weight

    Below I've attached the question - I don't know why this question is so difficult, perhaps I missed a lesson or such, however I've Benn working at it for ages and got nowhere...
  5. greg_rack

    Considerations for the FBDs of a parachutist traveling at terminal velocity

    There are a few things I'm not getting about this exercise and related diagram: -what does "force from parachutist" consists of? -if the terminal velocity is reached, then ##a=0## which means ##F_{tot}=0##, so shouldn't simply the sum of all forces pointing upwards be equal to the sum of all...
  6. NovaBlast

    What's the terminal velocity of a Boeing 737 in free fall from 12.496km

    Say that all the engines of a boeing 737 failed while it was 12.496km in the air and fell into freefall, what would its terminal velocity be and how long would it take to hit the ground
  7. rayjbryant

    Calculating the terminal velocity of a magnet falling through a copper coil

    The magnet being used % magnet dimensions [m] d = .0127; r = .00238; %mass of magnet [kg] m_w = .0017; % other constants u_0 = 1.26E-6; % permeability of free space constant T m/A g = 9.81; % gravitational constant in/s^2 %coil properties [22 gauge wire] [m] a = .00635; %radius w =...
  8. Saptarshi Sarkar

    Terminal Velocity of a Falling Parachutist

    I tried to calculate it by the way I know, i.e., setting the right hand side of the equation of motion to zero and getting v² = 25g = 2500 (taking g =10) => v = 50m/s But this answer is incorrect. How do I use the information of the initial velocity and why would it effect the terminal...
  9. T

    How come "terminal velocity" and "final velocity" are different?

    Homework Statement Someone shot the bullet perpendicular to the ground. And there is air resistance. Velocity of bullet is v^2 = Ae^(-2kx)-g/k upward v^2 = g/k-Be^(2kx) downward A,B is constant, g is a gravitational acceleration, k = c2/m , c2 is a resistance constant, m is a mass...
  10. Storm Savage

    Is there a terminal velocity upwards?

    We are all familiar with the concept of terminal velocity due to air friction in the direction towards the earth, but what about the other direction? Given enough applied force, is it possible to experience a terminal velocity upwards?
  11. liroj

    Terminal velocity of two balls with different masses

    Two objects of the same shape (say balls) fall through the Earth's atmosphere. For simplification, let's say that the air density is the same (some average sea level value) despite altitude change. One ball has considerably bigger mass than the other, but besides that, they're the same. Will...
  12. P

    Equation for falling objects that includes terminal velocity

    if an objects terminal velocity in air is 18m/second, when what would be an equation that describes its velocity from t0?
  13. J

    MHB Calculating Terminal Velocity

    Hi All, I am struggling with the question (attached) and was hoping to get some guidance and explanation on how to solve it. I`m thinking that it is force down is equal to force up? But I could be wrong. Any help greatly appreciated. Regards, James
  14. Henrique Orlandini

    Terminal velocity of a skier using a Momentum Balance

    Homework Statement [/B] A skier (mass M = 100 kg) going down a slope with inclination θ = 30°, sliding in a fluid-like snow (viscosity μ = 100 mPa*s) of thickness h = 0.01 m, using a pair of skis, each one with a surface area of As = 0.15 m2, reaches terminal velocity vt after some distance...
  15. Ushitha Dissanayake

    How do I find the terminal speed of a body in water?

    Homework Statement A baseball has a terminal speed of 42 m/s in air (ρ = 1.2 kg/m^3). What would be its terminal speed in water (ρ = 1.0 x 10^3 kg/m^3)? A) 0.05 m/s B) 1.5 m/s C) 18 m/s D) 42 m/s E) 1200 m/s Homework Equations D=½Cρ*Av^2 where the magnitude of the drag force (D), relative...
  16. Muhammad Danish

    B Resultant Force of a skydiver

    When a skydiver falls at terminal velocity, and opens his parachute, what will be the direction of the resultant force immediately after he opens his parachute? As far as I know is that the direction of acceleration will be upwards since his velocity is decreasing. I am a bit confused regarding...
  17. R

    How increased mass and drag affect speed

    Hello. I read an article about aerodynamics. http://www.cyclist.co.uk/in-depth/2873/fat-v-skinny-who-goes-downhill-faster I'm a little bit confused with this statement regarding mass, drag, and velocity: "When you increase the mass the speed increases by cubic function, whereas if you...
  18. P

    Increase in rising air bubble's terminal velocity

    Hi! As we know air bubble in the water rises due to buoyancy and quickly reaches its terminal velocity. What is more, as bubble rises the pressure decreases, consequently the volume of the bubble increases resulting in buoyancy becoming larger. So the terminal velocity doesn't remain constant...
  19. lichenguy

    Dimensional analysis problem

    Homework Statement A block of mass ##m = 1.00 kg## is being dragged through some viscous fluid by an external force ##F = 10.0 N##. The resistive force can be written as ##R = -bv##, where ##v## is the speed and ##b = 4.00 kg/s## is a phenomenological constant. You may ignore gravity (we...
  20. S

    Terminal Velocity Equation with a Vi greater than 0

    Doing a skydiving project where the two people collide and move at an intital velocity of 75.73 m/s. When i use the normal terminal velocity equation i get: V = sqrt((2*m*g)/(DpA)) = 63.82 m/s When D is 1 p = .9798 A = .835 Is the a formula that factors in Vi? Or does it slow down to its...
  21. T

    If a steel ball were to fall, how far away would it land

    Hello! Imagine you drop a steel ball of weight x from a variable height y. the ball hits a steel ramp on the ground which is at 45 degree's I would like to know how I could work out how far away the ball will land. I have had a good look around for this however the closest thing I can find...
  22. B

    Terminal velocity of a raindrop

    Homework Statement A raindrop of initial Mass ##M_0## starts to fall from rest under the influence of gravity. Assume that the drop gains mass from the cloud at a rate proportional to the product of its instantaneous mass and its instantaneous velocity ##\dfrac{dM}{dt} = kMV##, where ##k## is...
  23. R

    Falling question about terminal velocity

    Hey guys I have a question. Terminal velocity is 9.81mps correct? Which converts to basically 35kmph so does that mean hitting the ground from free fall after jumping out of an air plane would have the same effect as hitting a wall or something immobile and hard at 35kmph? Thanks
  24. D

    Is there a terminal velocity for expansion in a vacuum?

    For this question imagine an balloon that will never pop and contains infinite mass. This balloon materializes inside a perfect vacuum with no boundary. Is there a terminal velocity of the expansion of the balloon? If so, does the balloon gradually accelerate to this velocity or does it hit...
  25. Brage Eidsvik

    Terminal velocity of fluid in pipe

    Hello, How do you calculate the terminal velocity of a fluid through a pipe. My problem includes turbulent flow, very high reynold number, and water (incompresible).
  26. Markus Lervik

    Terminal Velocity: Solve Physics IA Problem

    Hello, I am finishing my IB internal assessment in physics. I have thrown four balls (with different masses, 400,450,475,500 grams) from a height, which is approximately 23 meters. My teacher told me to set up a graph which showed mass vs. vt^2. He said that the inverse of M=...
  27. Markus Lervik

    Thermal velocity of a soccer ball

    Hello, I am an IB HL Physics student. I am thinking of doing my IA on the thermal velocity of a soccer ball. I will be using a soccer ball shooter (machine) to simulate the thermal velocity. I have a couple of questions: what is the thermal velocity equation, which would fit for a soccer...
  28. C

    Penetration of falling object into sediment (after water)

    Hi All, Long time absentee from the forums hoping for some direction in my new research. I've been tasked to look into the stages of motion of objects (dropped from various heights), hitting a body of water (of various depths) and eventually hitting the seabed (of various sediment types). I am...
  29. jhan

    Constant Ratio of Drag coefficient and terminal velocity

    Guys,, please check my own way to get Drag coefficient and Terminal Velocity by given Drag force,.. okay,, lets for example: we know drag force is Fd= Cd*pf*v^2*A/2,, ill give little example (Cd=.02)*(pf=1027kg/m^3)*(v^2=.0025m/s)*(A=24m)/2 =( Fd .6162N) so drag force is .6162N,, okay..according...
  30. VNV

    Writing: Input Wanted Extraorbital Atmospheric Re-Entry: Terminal Velocity?

    Extra Orbital Atmospheric Re-Entry, or the Art of Leaping From Orbiting Starships onto Planets. Ignoring that my TITANs are donned in A.T.L.A.S. PCA and thereby protected by force-evaporating malarkey nodes, I want to know how they'd be in the middle of these jumps. In my book, a TITAN Super...
  31. Elvis 123456789

    How can I be sure of my numerical result?

    Homework Statement In this problem you will do numerical computer calculations. A skydiver of mass 75.0 kg jumps out of a plane at an altitude of 30.0 km above the surface of the Earth. His parachute fails to open. Assume there is no horizontal motion and the initial velocity is zero. We...
  32. S

    I Could the speed of light just be "terminal velocity"?

    Alright, so I'm by no means a trained physicist and most of what I know comes from sporadic readings on the internet, but I had a strange theory the other day. I'm more the type to think in visualizations or analogies rather than cold hard math, so I'll explain it the way the idea came to me...
  33. ThePizzaDeliveryGuy

    Average Passenger Plane Terminal velocity with added speed

    A passenger plane is traveling at a speed of 500 knots, has a mass of 72574.7792 kg, and has an altitude of 35,000 feet. If the pilot lost control of the plane and couldn't reduce speed or anything and the plane was going down at approximately a 40 degree angle, how long would you have until it...
  34. S

    Terminal Velocity of a Cylinder Freefalling Through a Fluid

    Hello :) I am an engineer and I am trying to analyse a system which basically contains a cylindrical body free-falling through a body of static water beginning with zero velocity. I am ultimately trying to find what the velocity of the object would be at a depth of 20m. In order to do this I...
  35. K

    Terminal Velocity of magnet down a copper tube

    Homework Statement I[/B] I am trying to find an equation that relates the velocity of 3 magnet when it falls down a copper tube to my measurement. The length of the copper tube is L=0.24m, The total mass of the 3 magnet is m = 4.98x10-3kg magnetic flux density B = 428mT, the thickness of the...
  36. John Lam

    Drag Force Physics Problem

    Homework Statement Assuming that the drag force magnitude is given by the equation D= bv, where b is the drag parameter and v is the instantaneous velocity magnitude of the object. (a) Show that the vertical displacement through which a dropped object must fall from to reach X% of its...
  37. T

    Spacecraft Reentry - Drag Decrease?

    I was given the following drag profile for a spacecraft upon reentry. I understand that the moment it enter's Earth's atmosphere it will be accelerated due to gravity and pick up speed which in turn increases drag however I don't understand why drag then decreases. Wouldn't density cause...
  38. J

    Conservation of energy at terminal velocity

    Homework Statement A spherical object is dropped from an elevation great enough such that it will achieve terminal velocity for some period of time before hitting the ground. Once terminal velocity is achieved what is gravitational potential energy converted to. Homework Equations Ug = mgh Ke...
  39. T

    Calculate terminal velocity when given cross sectional area

    Homework Statement Two packages are dropped from an airplane. A parachute can increase the cross sectional area of each packages by a factor of 31. The parachute on package 1 fails to open, and the terminal speed of package 1 is 10 m/s. The parachute on package 2 opens. What is the terminal...
  40. F

    Escape Velocity = Freefall from Height of One Radius?

    I was doing some calculations using the escape velocities from Earth, Moon and Mars. Then by chance I calculated the velocities attained when an object was "dropped" from a height of the radius on each of these bodies, assuming the acceleration due to gravity remained constant during the fall...
  41. C

    Acceleration in terminal velocity?

    I've just read somewhere that acceleration is zero when an object is at terminal velocity? I think it's wrong but wanted to check if I'm right? Yes the resultant force is zero but gravity doesn't disappear so presumably acceleration due to gravity is constant? Terminal velocity means constant...
  42. M

    Investigating terminal velocity

    Homework Statement So, we were given these instructions to find the terminal velocity reached by an object falling through the air: Equipment: bun-case; access to balance; calipers; metre rule; stopwatch. Instructions: 1. Record the mass of the bun-case 2. Measure with a recorded precision...
  43. I

    Terminal velocity of a bicycle under a constant force

    Hello! The total force F = m*a applied to the bicycle is F = F1 - a*v^2, where F1 is the initial force applied to the bicycle, a is a constant and v is the velocity. That means that the total force applied to the bicycle decrease as velocity increases, like a wind resistance decreases...
  44. Z

    An experiment from which you can calculate terminal velocity

    "Describe an experiment that could be carried out in order to measure the terminal velocity of an object falling under gravity. Include any equations you would use or calculations you would make." The only formula I can think of is F=ma, but I don't see how that is relevent. My train of...
  45. H

    Terminal velocity in space, is there one?

    Eg a particle is emitted by a supernova and starts accelerating toward our galaxy, what limits its speed to keep it less than c? Reasoning: its initial velocity was large, the acceleration due to mass of our galaxy is big allowing for initially it is smaller due to distance. Initial high...
  46. N

    Terminal speed-Skydiver

    Homework Statement I attached a screen shot of the problem. Homework Equations D= 1/2 C p A v^2 bv=mg The Attempt at a Solution I spent 3 long hours on this problem. I confused myself even more. Please help me understand what is going on.
  47. B

    Drag, terminal velocity, and force.

    Homework Statement Coal miners often find mice in deep mines but rarely find rats; let’s see if we can figure out why. A mouse is roughly 5 cm long by 2 cm wide and has a mass of 30 g; a rat is roughly 20 cm long by 5 cm wide and has a mass of 500 g. Assume that both have a drag coefficient CD...
  48. R

    Terminal velocity of loop falling through magnetic field

    Homework Statement https://physicsforums-bernhardtmediall.netdna-ssl.com/data/attachments/72/72755-bc8e4b32405460abcfa2d8e4880f7037.jpg [Broken] I'm trying to figure out the terminal velocity of the loop as it falls through the magnetic field (figure 7.20). 3. The Attempt at a Solution The...
  49. A

    Velocity as a function of time -- Terminal Velocity

    I am having trouble finding a staring place. My class requires us to use python to solve the equation. This problem requires me to use eulers method to solve it. My issues is that i am getting confused as of how to find the v(t). Its been a while since i have had to do advance physics like...
  50. I

    Drag time of terminal velocity?

    Hi all! How can we know the time and speed of the object before it reachs the terminal veocity, it will reach that, but when? (he's acceleration decreseases right) thanx