What is Revolutions: Definition and 101 Discussions

In political science, a revolution (Latin: revolutio, "a turn around") is a fundamental and relatively sudden change in political power and political organization which occurs when the population revolts against the government, typically due to perceived oppression (political, social, economic) or political incompetence. In book V of the Politics, the Ancient Greek philosopher Aristotle (384–322 BC) described two types of political revolution:

Complete change from one constitution to another
Modification of an existing constitution.Revolutions have occurred through human history and vary widely in terms of methods, duration and motivating ideology. Their results include major changes in culture, economy and socio-political institutions, usually in response to perceived overwhelming autocracy or plutocracy.
Scholarly debates about what does and does not constitute a revolution center on several issues. Early studies of revolutions primarily analyzed events in European history from a psychological perspective, but more modern examinations include global events and incorporate perspectives from several social sciences, including sociology and political science. Several generations of scholarly thought on revolutions have generated many competing theories and contributed much to the current understanding of this complex phenomenon.
Notable revolutions in recent centuries include the creation of the United States through the American Revolutionary War (1775–1783), the French Revolution (1789–1799), the Spanish American wars of independence (1808–1826), the European Revolutions of 1848, the Russian Revolution in 1917, the Chinese Revolution of the 1940s, the Cuban Revolution in 1959, the Iranian Revolution in 1979, and the European Revolutions of 1989.

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  1. S

    Centripetal Acceleration while Swinging a Stone on a String

    So my initial understanding is that it completes 5 revolutions per second. I converted the 5 rev to radians, so each revolution is 2pi. Now since I got angle of rotation I can plug it into the angular velocity formula which is Angular velocity= angle of rotation/ time. However since I don't have...
  2. anorlunda

    I Feynman's QED; 36,000 revolutions per inch for red light.

    In Feynman's book, QED, The Strange Theory of Light and Matter, page 27 he says, "As long as the photon moves, the stopwatch hand turns (about 36,000 times per inch for red light); when the photon end up at the photomultiplier, we stop the watch." I've been puzzling about the significance of...
  3. H

    Calculating how many revolutions it takes to reach the final speed

    11 rpm equals 1.15 rad/ sec not sure how this helps contribute to the question but I solved for it just in case
  4. B

    Rotational motion: Number of revolutions before a flywheel comes to rest

    Hi there I have been having a go at this question and I'm uncertain if my answer to part b) is valid? The problem is when I plug this into the calculator I get 6.379... revs however this doesn't make sense to me. 2*pi is roughly 6.28 radians so doing 4.061... rads / 6.28 rads = 0.647 revs...
  5. A

    A Why is ##\omega_c \tau >>1## for several revolutions?

    Hey, I read about charge carriers in semiconductors in a magnetic field. They write that for several revolutions ##\omega_c \tau >>1## holds. But I think for one revolution it is ##\omega_c \tau = 2 \pi##. (##\tau## is the scattering time) Why they do not write ##\omega_c \tau >> 2 \pi##...
  6. S

    Calculating revolutions per minute

    Homework Statement A centrifuge is a device in which a small container of material is rotated at a high speed on a circular path. Such a device is used in medical laboratories, for instance, to cause the more dense red blood cells to settle through the less dense blood serum and collect at the...
  7. V

    How to count the bicycle wheel revolutions by accelerometer

    Hi, I am setting the accelerometer (BMA250E) on the bicycle wheel hub. I want to count the wheel revolutions(each sine wave) but the Speed over 20km the x-axis(a) data will increase. My question is: How to count the sine wave when x-axis sine wave position move to high or low. Thanks.
  8. javii

    Calculate how many revolutions the flywheel turns

    Homework Statement [/B] Homework Equations I have calculated the kinetic energy and the total moment of inertia. https://www.physicsforums.com/file:///C:/Users/javad/AppData/Local/Temp/msohtmlclip1/01/clip_image002.png The Attempt at a Solution I really don't know how to solve the problem...
  9. hpthgpjo

    Finding angular acceleration from revolutions and velocity

    Homework Statement an object starts from rest and has a final angular velocity of 6 rad/s. the object makes 2 complete revolutions. find the object's angular acceleration. Homework Equations wf^2=wi^2+2αd The Attempt at a Solution Not sure what to do with the revolutions, would it take act as...
  10. C

    How many revolutions did the fish make?

    Homework Statement A fish starts at rest and uniformly accelerates. After 10 seconds, he is swimming around a rock at a rate of 3.14 rad/sec. a.) What's the magnitude of angular acceleration? b.) How many times did the fish circle the rock (how many revolutions?) Homework Equations a.)...
  11. B

    Determining revolutions of a wheel

    Homework Statement The picture to this problem is very basic so I don't think I have to draw one here. It's a picture of a clown juggling on a tightrope. The problem is: If the radius of the wheel on Puncho's unicycle is 0.25 m, and Puncho is riding with a velocity of 10 m/s, how many...
  12. D

    Calculating Revolutions for a Spinning Wheel | Circular Motion Problem

    Homework Statement A wheel spins at an angular speed of 2.50 rad/s for a total of 30.0s. How many complete revolutions will the wheel make during this time? A) 31.4 rev B) 19.3 rev C) 11.9 rev D) 75.0 rev Homework Equations W=Wo+(alpha)(t) θ=θo+Wot+1/2(alpha)t^2 W^2=Wo^2+2(alpha)(θ-θo) The...
  13. J

    Find Angular Velocity when given Angular Acceleration?

    Homework Statement Starting from rest, a spinning compact disk undergoes an angular acceleration of 5.0 rad/s^2. What is the angular speed of the disk after 3 revolutions? Homework Equations a=Δω/Δt ω=Δθ/Δt The Attempt at a Solution I do not understand how to solve this equation when I am not...
  14. almarpa

    Quantum Griffiths' revolutions in 20th century physics

    hello all Prior to my studies in QM I would need a brief intro to quantum physics. I know there are lot of books on modern physics that cover these topics, but really like Griffiths' style, and my QM textbook is precisely his QM book. So, my question is if "revolutions in 20th century physics"...
  15. K

    Electron revolutions in Bohr model

    Homework Statement On the average, a hydrogen atom will exist in an excited state for about 10-8 s before making a transition to a lower energy state. About how many revolutions does an electron in the n = 2 state make in 10^-8 s? Homework Equations L = mvr = Iω = nħ rn = n2a0/Z The Attempt...
  16. K

    How can I find an objects # of revolutions as it accelerates

    The crankshaft in a race car goes from rest to 3180rpm in 2.4s . a) What is the crankshaft's angular acceleration? >>Which I found to be ~140rad/s^2 b) How many revolutions does it make while reaching 3180rpm ? How can I find the answer to b) ? I'm not even sure where to start..
  17. E

    Revolutions per second for hydrogen molecule

    Homework Statement The distance between the both nucleons in the H2 molecule is 0.0741 nm The energy for the 3 lowest radiation levels of the molecule are: ##E_{0}=0 \\ E_{1}=0.0151 eV \\ E_{2}=0.0453 eV## How many revolutions per second does the molecule rotate with in the different states...
  18. M

    Understanding Diesel Engine Cycles and Revolutions

    Homework Statement In a diesel engine each cycle takes two revolutions and there are 6 cylinders. Homework Equations what does " each cycle takes two revolutions" mean and are there a relation or equation between cylinder number and calculation of engine power? The Attempt at a...
  19. M

    Volume of solids of revolutions. (Integral problem)

    Homework Statement A function is given at y = \sqrt{x-x^2} Find the volume of the solid of the revolution around the x axis. Not sure if this is the correct translation, but find the volume when you revolve the function around the x axis. The object in question is a sphere. What does the...
  20. W

    Amount of Revolutions Based on Multiple Radii

    Homework Statement A chainwheel of a bicycle has a radius of .09 m, the radius of the smallest cogwheel (the “highest” gear) is .01 m, and the radius of the rear wheel is .35 m. At what rate (in revolutions per minute) must you be pedaling in order for the bicycle to have a forward speed of...
  21. F

    Revolutions per minute, angular deceleration

    Hi all, Homework Statement The motor driving a large grindstone is switched off when a rotational speed of 360 rpm has been achieved. After 15s the speed has decreased to 210rpm. If the angular deceleration remains constant, how many additional revolutions does the stone make before coming to...
  22. S

    Circular Motion, Revolutions from diameter, time and speed

    Homework Statement A car is moving at a speed of 20 m/s in 4 seconds and the car's tire is 38cm which is its diameter. How many revolutions did your tires make? Homework Equations Relevant Equations, T=2∏r / v The Attempt at a Solution My attempt at a solution: To get...
  23. S

    Calculating Revolutions in Circular Motion: A Tire's Journey in 4 Seconds

    A car is moving at a speed of 20 m/s in 4 seconds and the car's tire is 38cm around which is its diameter. How many revolutions did your tires make? Relevant Equations, T=2∏r / v My attempt at a solution: To get the distance travelled=20 m/s (4 sec.) = 80 m 2∏(0.19m)= 1.19 m 80m /...
  24. V

    Dimentional Anaylsis: Solving for Revolutions

    NASA's Cassini mission to Saturn released a probe on December 25, 2004, that landed on the Saturnian moon Titan on January 14, 2005. The probe, which was named Huygens, was released with a gentle relative speed of 31 cm/s. As Huygens moved away from the main spacecraft , it rotated at a rate of...
  25. J

    Volumes of Solids of Revolutions Help

    Homework Statement Find the volume of the solid obtained by rotating the region bounded by the given curves about the specified line. Sketch the region, the solid, and a typical disk or washer. y=x, y=0, x=2, x=4; about x=1 The Attempt at a Solution one of the radii is x=y but I am...
  26. B

    Why Do We Use Frustrums Instead of Disks to Find the Surface of Revolution?

    When I learned solids of revolutions, we divided the solid into infinitely thin "disks" and then summed up their individual volumes to get the volume of the surface. Now in surface of revolutions, we are divided the solid into infinitely thin fustrums and summing up their individual surface...
  27. C

    Revolutions of a tire and angle in radians thru warranty

    Homework Statement The tires on a new car have a radius of .275 meters and are warranted for 75,000km a)what is the angle in radians that one of these tires will rotate thru in the warranty period? b) how many revolutions does this make?Homework Equations 1rev = 2pi radians circumference =...
  28. B

    Revolutions frequency after collision

    Homework Statement A bar, whose mass is 10kg, is 3 cm long and is free to rotate about a vertical axle through its centre. At the beginning, the bar is vertically quiet. Then, the two extremities are hit at the same time by two bullets, one by the left and the other by the right. Their masses...
  29. S

    Linear speed/how many revolutions are made?

    Homework Statement a quarter back throws a pass that is a perfect spiral, and the spins at 7.7 rev/s. the linear speed is 19 m/s and at an angle 55. if the ball is caught the same height it is thrown, how many rev. has the ball made while in the air? Homework Equations ω^2 = ωnot^2 + 2(alpha)...
  30. M

    Calculating Revolutions in 1.0 s with Given Tension and Moment of Inertia

    Problem: A large fish strikes bait cast by a fisherman with a rod and reel. The fish creates tension in the line of 65 N. How many revolutions of the reel occur in 1.0 s if the reel has a moment of inertia of 4.0 * 10^-3 kg-m2 and the radial distance of the line from the reel’s axis is 4.0...
  31. J

    No slip wheel, distance covered, find revolutions

    The radius of each wheel on a bicycle is 0.400 m. The bicycle travels a distance of 3.0 km. Assuming that the wheels do not slip, how many revolutions does each wheel make? This problem seems so simple but none of the possible answers available seems correct. My work r = 0.4 m x = 3...
  32. D

    Revolutions problem y=-x^2+12x-35

    Urgent! Advice Needed I am currently taking calculus II, and didn't do so hot on the midterm yesterday. I had to take the test on webassign(proctored). The instructor says partial credit will be given, but my webassign score was a 50%. I did not have a problem with the calculus involved, but...
  33. J

    Volumes of solids of revolutions

    Homework Statement In the question your working with the region bounded by the two curves y=x^2 and y=x^3. In the first part of the question you had to revolve the region around the x-axis and find the area which I managed to do by subtracting two areas from each other. The second part of...
  34. C

    Rotation Problem: determine the number of revolutions

    Homework Statement It's been a while since I've done a problem like this, and I wanted to see if anyone could spot my errors. I know that I'm making an incorrect assumption somewhere, but can't quite figure it out. The problem states: A 150 lb man is on the edge of a diving board, 30 feet...
  35. J

    Solving an Accelerating Car's Revolutions

    Homework Statement A car is coming to a top over a distance of 96m Vi = 20m/s r = 25cm find the intial angular velocity, angular acceleration, total revolutions Homework Equations w = v / r angular acceleration = change in w / t d = (Vi + Vf / 2) t The Attempt at a Solution...
  36. R

    Gravitational pull (revolutions)

    I am working on my own laws of physics because I am extremely bored. I am making a law or revolution (objects revolving around other objects) and thought of a few questions that hopefull you guys can help me with. Here they are... 1) In a vacuum, where the only gravitation pull is between you...
  37. rootX

    Analyzing the Impact of Revolutions on Prosperity: A Scientific Approach

    Do revolutions lead to prosperity? or Do we need revolutions for prosperity? or Is revolutions one of the factors that determine prosperity? defn Revolutions : Overthrowing the governments Prosperity : Good living standards e.g. literacy and life expectancy. Scope: Only last 500 years...
  38. MathWarrior

    Soild Revolutions, surface area etc.

    In calculus when you learn solids of revolution in relation to surface area or volume is there any specific uses that someone could enlighten me on in which this would be used. The only example I can think of is a lathe, and calculating its mass using the volume. Other then that I haven't seen...
  39. K

    How many revolutions will the car go through?

    Homework Statement A car starts from rest on a curve with a radius of 190m and accelerates at 0.800 m/s^2 . How many revolutions will the car have gone through when the magnitude of its total acceleration is 2.60 m/s^2 ?Homework Equations The Attempt at a Solution I have tired the magnitude...
  40. S

    Calculating amount of revolutions

    Homework Statement A high-speed drill reaches 2760 rpm in 0.260 s. Through how many revolutions does the drill turn during this first 0.260 s? 2. The attempt at a solution UPDATED: Here's what I have right now 2760 rpm * (2n/1 rev) * (60 s / 1 min) = 1040495.49 rad/s 1040495.49 rad/s *...
  41. W

    Circular motion - finding revolutions?

    i've been struggling for hours upon hours attempting to find the answer to simple problems and I'm extremely depressed.. how do i find the amount of revolutions if I'm given the constant angular acceleration (rad/s^2) and the time (seconds)?
  42. T

    How Many Revolutions Does a Turbine Make When Coasting to a Stop?

    Homework Statement An electric-generator turbine spins at 3460.0 rpm. Friction is so small that it takes the turbine 14.9 min to coast to a stop. How many revolutions does it make while stopping? (Do not include a unit with your answer.) Homework Equations rev/min * 1min/60sec =...
  43. J

    Rotational Kinematics? Revolutions of a propeller?

    Homework Statement An airplane engine starts from rest; and 2 seconds later, it is rotating with an angular speed of 420 rev/min. If the angular acceleration is constant, how many reovlutions does the propeller undergo during this time? Homework Equations \theta = \omega 0 t +1/2 \alpha...
  44. M

    Revolutions and angular speeds

    Homework Statement A car initially traveling at 33.8 m/s undergoes a constant negative acceleration of magnitude 1.80 m/s2 after its brakes are applied. (a) How many revolutions does each tire make before the car comes to a stop, assuming the car does not skid and the tires have radii of 0.330...
  45. F

    Number of revolutions a disk has made after a given time

    [b]1. A computer hard disk starts from rest, then speeds up with angular acceleration of 218 rad/s^2 until it reaches its final angular speed of 6660rpm. How many revolutions has the disk made 10.1s after it starts up? [b]3. The Attempt at a Solution . I have no idea how to find the...
  46. H

    Revolutions of a driving shaft

    Homework Statement How many revolutions does a driving shaft of an eight cylinder four stroke engine perform until every cylinder has ignited once ? Homework Equations 4 - 8 - 6 - 2 The Attempt at a Solution Moreover, I would like to have information and understand the logical...
  47. S

    Period of Revolutions of a Planet

    Homework Statement A neutron star has a radius of 10,000 km, and takes a planet 30 days to complete one revolution around the star. When the star collapses, the new radius is 3 km. Find the new period of revolution of the newly formed neutron star. Homework Equations T=2(pi)/omega omega...
  48. Y

    Revolutions of a Sphere on an Incline

    Homework Statement A sphere of radius 0.19 meters starts from rest at the top of an incline at a height of 7 meters. The angle of the incline is 36 degrees. How many revolutions does the sphere make as it rolls to the end of the incline without slipping?
  49. L

    Number revolutions with constant angular decelleration

    # revolutions with constant angular decelleration 1. A well-lubricated bicycle wheel spins a long time before stopping. Suppose a wheel initially rotating at 120 rpm takes 65 s to stop. If the angular acceleration is constant, how many revolutions does the wheel make while stopping...
  50. A

    How Fast Must an Astronaut Spin for 2.89g Acceleration?

    Homework Statement As their booster rockets separate, Space Shuttle astronauts typically feel accelerations up to 3g, where g = 9.80 m/s2. In their training, astronauts ride in a device where they experience such an acceleration as a centripetal acceleration. Specifically, the astronaut is...