Revolutions Definition and 98 Threads

Homework Statement An astronaut is rotated in a centrifuge of radius 4.0 m. Homework Equations v = omega * radius a = v^2/radius The Attempt at a Solution Ok, so I first found the omega for this acceleration, which came out to be omega = 3.56179 s^-1 then I decided...

Homework Statement An electron of speed v enters a region of magnetic field B directed normally to its velocity and is deflected into a circular path. Find an expression for the number of revolutions per second the electron will make. If the electron is replaced by a proton, how does your...

SOLVED Given initial angular velocity of wheel, find revolutions to rest Homework Statement As a result of friction, the angular speed of a wheel changes with time according to d \vartheta / dt = 4.1e-.088335775t where the initial angular velocity is 4.1 rad/s. Find the number of...

Homework Statement Sam drops his ring in the mall. It goes rolling away from him at a velocity of 3.0 m/s. It has a radius of 0.50cm. After rolling 1.0 m how many revolutions has it made? Homework Equations vcm= rw The Attempt at a Solution vcm 3.0x 2 pi = 18.84 0.50x 18.84= 9.42

Spinning Disk A disk with a diameter of 0.06 m is spinning with a constant velocity about an axle perpendicular to the disk and running through its center. a) How many revolutions per second would it have to rotate in order that the acceleration of the outer edge of the disk be 15 g's...

Homework Statement A 5.0m diameter merry go round is initially turning with a 4.0s period. It slows down and stops in 20 s. How many revolutions does the merry go round make as it stops? Homework Equations w=v/r v=2(pi)r/T The Attempt at a Solution v=2(pi)2.5/4 =3.9 m/s w=v/r...

1. A variable speed electric drill motor turning at 100 rev/s is uniformly accelerated at 53.0 rev/s2 up to 210 rev/s. How many turns does it make in the process? 2. (Accel f - Accel) i x speed 3. I took 210 - 53 = 157 and multiplied that by 100 and that gave me 15,700 rev. This...

Homework Statement The angular speed of an automobile engine is increased at a constant rate from 1500 rev/min to 3900 rev/min in 14 s. (A) What is its angular acceleration in revolutions per minute-squared? (B) How many revolutions does the engine make during this 14 s interval...

Homework Statement There is an attachment for the picture. question is, How many revolutions does the object make during the first 4 s? Homework Equations The Attempt at a Solution I attempted to solve this by dividing 20 by 2pi, but apparently, that was wrong. Any help?

i am comlpetely stuck on this problem Two satellites are in circular orbits around Jupiter. One, with orbital radius r, makes one revolution every 16 h. The other satellite has orbital radius 4.0r. How long does the second satellite take to make one revolution around Jupiter? any help please?

Homework Statement A boy whirls a ball on a string in a horizontal circle of radius 1.0 m. How many revolutions per minute must the ball make if its acceleration towards the center of the circle is to have the same magnitude as the acceleration due to gravity? Homework Equations a=v^2/R...

Homework Statement You switch a food blender from its high to its low setting; the blade speed drops from 3100 rpm to 1300 rpm in 2.1 s. How many revolutions does it make during this time? Homework Equations \omegai = \frac{3100 rpm * (2 * pi)}{60} = 324.6 rad/sec \omegaf = \frac{1300 rpm...

If I have a ball/sphere is released from rest, rolls (without slipping) down a ramp, then drops from the table the ramp is on, how many revolutions does the ball make during the fall? The diameter of the ball, height of the ramp, and height of the table are known. And I calculated the...

There are two disks of uniform density that touch at one point. their masses are in a ratio of 1:9. how many revolutions does the smaller disk make as it makes one rotation around the big circle? (assume that the disks do not slip) This is my try: a is small circle b is big circle...

How many revolutions does the object make during the first 4 s well the area under the graph of the angular velocity versus time graph is 60 but I do not know how that helps. Any help would be appreciated. Stephen

Here is the question: The Wall of Death in an amusement park is comprised of a vertical cylinder that can spin around the vertical axis. The radius of the cylinder is 3.5 m and the coefficient of static friction between the rider and the wall is 0.32. Find the minimum number of revolutions per...

Hi everyone, Homework Statement An automobile tire is rated to last for 35,000 miles. To an order of magnitude, through how many revolutions will it turn? Homework Equations 2pir The Attempt at a Solution d=3f=.9144m r=.9144/2 =.4572 n(2pi)r=35,000miles...

Homework Statement An electric-generator turbine spins at 3600rpm . Friction is so small that it takes the turbine 16.0 min to coast to a stop.How many revolutions does it make while stopping? Homework Equations The Attempt at a Solution (3600rev/min)(16.0min)=57600 i...

[SOLVED] Centrifuge Revolutions? Homework Statement A centrifuge accelerate from rest to 15,000 rpm in 240s. Through how many revolutions did it turn in this time? Homework Equations am i approaching this problem correctly? The Attempt at a Solution 15000rev/m (1m/60s) (240s) =...

Homework Statement A string is wound tightly around a wheel. When the end of the string is pulled through a distance of ? cm, the wheel rotates through ? revolutions. What is the radius of the wheel? Homework Equations The Attempt at a Solution i'm confused about this...

A car is designed to get its energy from a rotating flywheel with a radius of 1.90 m and a mass of 510.0 kg. Before a trip, the disk-shaped flywheel is attached to an electric motor, which brings the flywheel's rotational speed up to 1008.0 rev/min. (a) Find the kinetic energy stored in the...

[SOLVED] Revolutions per sec (centripital acceleration) Homework Statement As their booster rockets seperate, space shuttle astronauts typically feel acclerations up to 3g where g= 9.80ms^2. In their training astronauts ride in a device in which they experience such accelrations as...

Homework Statement A turntable reaches an angular speed of 45.0 rpm, in 2.1 s, starting from rest. (a) Assuming the angular acceleration is constant, what is its magnitude? _2.24_rad/s2 (b) How many revolutions does the turntable make during this time interval? ______ rev...

Homework Statement Starting from rest, a 12cm diameter compact disk takes 2.7s to reach its operating angular velocity of 2005rpm. Assume that the angular acceleration is constant. The disk's moment of inertia is 2.5 x 10-5 kgm^2. a.) How much torque is applied to the disk? b.) How many...

# of Revolutions made I had the same question as someone else here, but they figured it out but nothing was said in the post. As such, I was asked to make a new thread.. So, pretty much, I have this question: 1. Homework Statement A car starts from rest on a curve with a radius of 110 m...

arr, i am so confused, is that tangential accelaration? Homework Statement A car starts from rest on a curve with a radius of 110 m and accelerates at 1.20 m/s^2. How many revolutions will the car have gone through when the magnitude of its total acceleration is 2.20 m/s^2? Homework...

I'll just ask one question at a time as I don't want to spam up the forum!:cool: Homework Statement Find the area of the region enclosed by the curves y²=4+x and x+2y=4. [b]2. The Attempt at a Solution Well I know I have to transpose the two equations to make y the subject, but for...

Homework Statement A hydrogen atom exists in an excited state for typically 5.79 ns. How many revolution would an electron make in the n=2 state before decaying? Homework Equations L=m*v*Rn=h(bar)*n w=v/Rn Rn=n^2*Ao Ao=.053 nm The Attempt at a Solution Rn=4*.053=.212 nm...

Homework Statement A flywheel has shape as a homogeneous cylinder with mass m = 40,0 kg and radius r = 0,50 meters. The cylinder is rotating round the axis of symmetry, and is runned by a motor with constant angular velocity (w0). When the motor is switched off, the cylinder is affected by a...

I've attached the problem as an image. I solved 20 and 21 very easily. For 22, my obvious instinct was to set dtheta/dt to 0, but that's an unsolvable equation. I'm obviously missing something key in solving 22. What is it?

Hi, Homework Statement In a simple model of the hydrogen atom, the electron moves in a circular orbit of radius 0.053 nm around a stationary proton. How many revolutions per second does the electron make? Homework Equations F = (kq1q2)/r^2 = (mv^2)/r v = wr The Attempt at a...

I am confused on how to find m/s in the following problem: r = 2.6km one revolution of circle = 360s I need it for ac = v^2/r Thanks!, -Mike

A sample of blood is placed in a centrifuge of radius 19.0 cm. The mass of a red blood cell is 3.0 10-16 kg, and the magnitude of the force acting on it as it settles out of the plasma is 4.0 10-11 N. At how many revolutions per second should the centrifuge be operated? I converted 19cm...

There is a glass chamber that is to be filled with water. The chamber is divided into two parts, the outer being filled with water and the inner being empty. The chamber is such that a person can stand inside without getting wet. It is modeled by the equations f(x) = \frac{243}{1820x^2} -...

An object of mass 4.0 kg is whirled in a horizontal circle of radius 0.40 m with a constant speed. If the tension in the wire is 80 N, a=20 m/s, v= 2.83m/s, T= 0.89 s find: d the number of revolutions made every minute.

A disc of moment of inertia 29.1 kg m2 is made to rotate about an axis through its centre by a torque of T . The disc starts from rest and, after {t} s, has kinetic energy {k} J. The torque is removed when the disc is rotating at 8.0 rad s-1 . An opposing torque of 13.2 N m is applied to slow...

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 bottom of the...

We have already had mechanical revolutions. What happens when AI and software develops to the point where 1 professional program operator can do the work of 10 professional engineers/surveyors/etc.? What happens when buying a robot is cheaper than buying the same amount of human unskilled...

According to the Bohr theory, how many revolutions will an electron make in the first excited state of hydrogen if the lifetime in that state is 10^-8? Basically do I find the speed of the that the electron moves in this excited state then get the distance that a revolution is and divide it...

Q: A disk of radius 2.40 cm and mass 1 kg is pulled by a string wrapped around its circumference with a constant force of 0.36 Newtons. What is the angular velocity of the disk to three decimal places after it has been turned through 0.85 of a revolution? So I started by obtaining my degrees...

The rotor of an electric motor has rotational inertia I am = 2.5*10-3 kg · m2 about its central axis. The motor is used to change the orientation of the space probe in which it is mounted. The motor axis is mounted along the central axis of the probe. The probe has rotational inertia Ip = 8 kg ·...

An electron of mass (m=9.1*10^(-31)kg) orbits a proton at a distance of 5.3*10^(-11)m. The proton pulls on the electron with an electric force of 9.2*10^(-8)N. How many revolutions per second does the electron make? This is what I did: m=9.1*10^(-31)kg v=5.3*10^(-11)m T=9.2*10^(-8)N...

An electron of mass (m=9.1*10^(-31)kg) orbits a proton at a distance of 5.3*10^(-11)m. The proton pulls on the electron with an electric force of 9.2*10^(-8)N. How many revolutions per second does the electron make? This is what I did: m=9.1*10^(-31)kg v=5.3*10^(-11)m T=9.2*10^(-8)N...

A clump of mud is attached to the outside of a bicycle wheel, radius 700mm. how many revolutions per second does this wheel have to spin to fling off the mud if the coefficient of static friction attaching it to the wheel is 0.64. The real trouble I am having with this is find the normal...

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How do you get the volume of an expanding object? For example: A sphere's is increasing at 12ft/sec, the volume is 36, how fast is the surface area of a sphere V=4*pi*r^3/3 S=4*pi*r^2 dV/dt= 12 So i took the derivative of the volume function dV/dt=4*pi*r^2*dr/dt 12=4*pi*r^2*dr/dt...

Imagine rolling a coin with a radius of 1 unit on a flat surface. To get translated 2[pi] units, the coin must obviously roll 1 revolution. (the angle swept is 2[pi] and the arc length covered equals to 2[pi]*r = 2[pi]*1 = 2[pi]. Now imagine rolling a coin on another stationary coin with the...

How many revolutions per minute would a 15m diameter Ferris wheel need to make for the passengers to feel weightless at the topmost point?