Revolutions Definition and 98 Threads

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...

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...

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

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...

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##...

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...

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.

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...

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...

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.)...

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...

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...

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...

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"...

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...

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..

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...

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...

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...

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...

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...

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...

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 /...

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...

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...

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...

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 =...

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...

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)...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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...

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 *...

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)?

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 =...

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...

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...

[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...

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...

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...

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?

# 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...

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...