What is Angular acceleration: Definition and 567 Discussions

In physics, angular acceleration refers to the time rate of change of angular velocity. As there are two types of angular velocity, namely spin angular velocity and orbital angular velocity, there are naturally also two types of angular acceleration, called spin angular acceleration and orbital angular acceleration respectively. Spin angular acceleration refers to the angular acceleration of a rigid body about its centre of rotation, and orbital angular acceleration refers to the angular acceleration of a point particle about a fixed origin.
Angular acceleration is measured in units of angle per unit time squared (which in SI units is radians per second squared), and is usually represented by the symbol alpha (α). In two dimensions, angular acceleration is a pseudoscalar whose sign is taken to be positive if the angular speed increases counterclockwise or decreases clockwise, and is taken to be negative if the angular speed increases clockwise or decreases counterclockwise. In three dimensions, angular acceleration is a pseudovector.For rigid bodies, angular acceleration must be caused by a net external torque. However, this is not so for non-rigid bodies: For example, a figure skater can speed up her rotation (thereby obtaining an angular acceleration) simply by contracting her arms and legs inwards, which involves no external torque.

View More On Wikipedia.org
Recent contents Top users
  1. J

    Are angular displacement, angular velocity, and angular acceleration, vectors?

    This my first post on this very helpful forum. So are angular displacement, velocity, and acceleration actually vectors? My Physics book does not really give me a straight answer. Plus, if they are, why do they not have the classic vector notation of the arrow above \theta, \omega, and...
  2. T

    Solving Angular Acceleration: Tips and Help for Inclined Planes and Formulas

    Homework Statement http://img166.imageshack.us/img166/6047/cilinderox6.jpg Homework Equations Tangent Acceleration, Linear Acceleration The Attempt at a Solution I tried to made a free body diagram but i got confused with the inclined plane I am stuck there. Also with the...
  3. X

    Angular Acceleration of a Model Rocket

    Homework Statement I'm getting this problem wrong and I'm not quite sure why. The 200 g model rocket shown in the figure generates 4.0 N of thrust. It spins in a horizontal circle at the end of a 100 g rigid rod. What is its angular acceleration (in rad/s2)? Homework Equations...
  4. D

    Angular Acceleration Homework: 1014.65°, 17.97 rad/s

    Homework Statement wheel rotates w constant acceleration 3.65rad/s2 angular speed is 3.00 rad/s at t=0 a)what angle does wheel rotate between t=0 and t=3.67s? b)what is angular speed of wheel at 4.1s? Homework Equations wt+1/2alphat (3.00rad/s)(3.67t)+1/2(3.65rad/s2)(3.67)2=17.70rad...
  5. P

    Angular acceleration of one rotating object fixed to another rotating object

    Homework Statement Given that a wheel with w(1) = -44i, is mounted on a turntable with w(2) = 35k, determine overall angular velocity and acceleration. Give both magnitude and direction. Homework Equations a = w(1) X w(2) ? The Attempt at a Solution I got the correct angular...
  6. A

    Angular Acceleration and Gravity

    Hello all, The other day I observed an occurrence in my Physics class which I do not understand. The teacher set up a rotating platform with a second platform attached to it, so it made a 45 degree angle with the rotating platform. He then proceeded to put a ball at the top of the second...
  7. C

    What is the initial acceleration of end B in a suspended rod system?

    A rod of length 61.0 cm and mass 2.10 kg is suspended by two strings which are 37.0 cm long, one at each end of the rod. The string on side B is cut. Find the magnitude of the initial acceleration of end B.
  8. L

    Am i going about this angular acceleration question the right way?

    Homework Statement A 0.023 g 1.0 inch long second hand on a wristwatch. Find its average angular acceleration? Homework Equations av=w/t The Attempt at a Solution so would i just do 0.023 g divided by 1 minute?
  9. L

    Angular Acceleration (I don't see HOW I can be wrong?)

    My friend in introductory physics came to me for help today. He has a test on angular momentum, acceleration etc. I figured, with me in upper-division physics courses, I'd be able to help him out. Well, I guess I was dead wrong. In half an hour I couldn't figure out a SINGLE THING. I don't...
  10. S

    Angular Acceleration of a grinding wheel

    Homework Statement A vertical grinding wheel is a uniform disk of mass 62 kg and radius 45 cm. It has a handle of radius 69 cm of negligible mass. A 25-kg load is attached to the handle when it is in the horizontal position. (a) Neglecting friction, find the initial angular acceleration of...
  11. I

    How to find angular acceleration

    Homework Statement A propeller slows from 450 rev/min to 200 rev/min in 3.50 s. What is its angular acceleration? Homework Equations ac = v^2/r and v = rw The Attempt at a Solution I know this is probably a simple problem, but what do the variables in the relevant equations refer to?
  12. A

    Solving Angular Acceleration of a Rod-Ball System

    Homework Statement A rod with mass M and length L is mounted on a central pivot. A ball is attached at the end of the rod. The rod initially makes an angle q = 27^{\circ} with the horizontal. The rod is released from rest. What is the angular acceleration immediately after the rod is...
  13. B

    Angular Acceleration Question

    Homework Statement A wheel is spinning at 800 rad/s. A torque is applied to the wheel until it stops spinning 14 seconds later. What is the angular acceleration, and how many revolutions did it go through? v=800 read/s t=14 s Homework Equations angular acceleration = delta w...
  14. A

    Angular Acceleration of Poll: Find the Equation

    Homework Statement Hey guys. I got this poll which is at one side connected to a wall and is being released from a horizontal state. his length is L and mass m. I need to find the angular acceleration of the poll as a function of the angle. I got this answer in the pic but according to...
  15. X

    Calculating coefficient of kinetic friction through angular acceleration

    A potter's wheel is 101 kg and has radius of 0.483 meters and is freely rotating at 71.9 rev/min. the potter can stop the wheel in 6.54 s by pressing against the rim and exerting a radially inward force of 103 N. find coefficient of kinetic friction. I found alpha=71.9 x 2 x pi/60sec/ 6.54=...
  16. S

    Angular acceleration of a seesaw

    Homework Statement There is a seesaw. The pivot point is closer to the left side than the right side. Let`s call the left length of the beam L1 and the mass on the left side m1. The right sideof the beam is L2 and the mass is m2. Information is L1 = 0.990 m, L2 = 1.78m, m1 = 4.40 kg, and m2...
  17. J

    Finding a max angular acceleration

    Given is a 6' long 40 lb bar hung horizontally by a pin O at its end. It is released from its horizontal position and hits a stopper after reaching a 30 degree angle with the horizontal position at which it started. I am asked to find the value x for which the angular velocity is a maximum and...
  18. I

    Calculating Torque & Angular Acceleration of a Current Loop

    Homework Statement A small current loop of area A = 1.5cm^2 carries current I = 3.6mA. What torque acts on it in a lab where its magnetic moment is perpendicualr to the Earth's magnetic field of 4.2 x 10^-5 (b) Find its angular acceleration if its rotational inertia about a diameter is...
  19. M

    Angular Acceleration of a hammer

    Having a bit of trouble with this question right here. If anyone could give some guidance it would be appreciated. A hammer is being accelerated at 15 rad/s^2. Given a radius of rotation of 1.7mm what are the magnitudes of the radial and tangential components of acceleration when the...
  20. C

    Calculate Angular Acceleration & Time of Toy Car w/Vo, Vf, R, & C

    1. a) A X kg toy car accelerates at constant rate from Vo m/s to Vf m/s in C revolutions while going around a circular track of radius R cm. Find: - α, the magnitude of the angular acceleration of the car. - t, the time it took to reach the final speed 2. To calculate the angular...
  21. G

    Angular Acceleration Problem

    Homework Statement The Attempt at a Solution I thought I could take the second derivative and get the angular acceleration from which I could use where ω is the angular velocity, is the linear tangential acceleration, and r is the radius of curvature. But for some reason, it didn't...
  22. O

    Angular Acceleration: Find Angle in 2 Seconds

    Homework Statement A wheel accelerates with constant angular acceleration of 6 rad/22. If the initial angular velocity is 6 rad/s. what is the angle in degrees that the wheel rotates through in 2 seconds? Homework Equations 360 degrees = 2pi radians The Attempt at a Solution...
  23. M

    Angular Acceleration of a bicycle

    A bicycle has wheels of 0.8 m diameter. The bicyclist accelerates from rest with constant acceleration to 22 km/h in 13.7 s. What is the angular acceleration of the wheels? relevant equations: omega = omega initial + alpha * t 22km/h = 6.11m/s I did 6.11m/s * 13.7s = 83.7207 to get the...
  24. B

    Angular Acceleration. Im totally lost

    Homework Statement A computer disk is turned on starting from rest and has constant anglular acceleration. If it took 0.570s for the drive to make its second complete revolution, how long did it take to make the first complete revolution? Also what is its angular acceleration Homework...
  25. G

    Help With Angular Acceleration

    Homework Statement A meter stick is hinged at its lower end and allowed to fall from a vertical position. With what angular speed does it hit the table?Homework Equations V = rW (Not sure?) The Attempt at a Solution I have no clue where to even start with this problem, given the small amount...
  26. M

    Angular Acceleration of a system.

    Homework Statement Two pulley wheels, or respective radii R1 = 0.34 m and R2 = 0.64 m are mounted rigidly on a common axle and clamped together. The combined moment of inertia of the two wheels is I + 1.2 kg*m^2. Mass m1 = 25 kg is attached to a cord wrapped around the first wheel, and another...
  27. R

    Physic tangential and Angular Acceleration

    Homework Statement In a Beams ultracentrifuge, a 20.3 cm long rotor is suspended magnetically in a vacuum. Since there is no mechanical connection to the rotor, the only friction is the air resistance due to the few air molecules in the vacuum. If the rotor is spinning with an angular speed of...
  28. H

    Angular acceleration of a pendulum on an accelerating train

    If I hang a pendulum on the ceiling of an accelerating train (with an initial angular displacement), how would the angular acceleration be affected? My intuition told me that the angular acceleration of the pendulum should be affected by the acceleration of the train. But...whether the...
  29. L

    Angular acceleration on a rod about an axis

    Homework Statement A long, 1 kg uniform rod and 1.4 m length, is supported at the left end by a horizontal axis into the page and perpendicular to the rod. The right end is connected to the ceiling by a thin vertical thread so that the rod is horizontal. The thread is burned by a match...
  30. A

    Angular acceleration problem Help

    A space station is constructed in the shape of a wheel 23 m in diameter, with essentially all of its 7.9×10^5 kg mass at the rim. Once the station is completed, it is set rotating at a rate that requires an object at the rim to have radial acceleration g, thereby simulating Earth's surface...
  31. I

    Calculating Angular Acceleration

    Homework Statement Find angular acceleration. Homework Equations \omega=\frac{2\pi}{t} \frac{\delta*\omega}{\delta*t}=a_{angular} The Attempt at a Solution \frac{\delta*\omega}{\delta*t}=-1*2\pi*t^{-1-1} -2\pi*t^{-2}=\frac{-2\pi}{t^2} \frac{-2\pi}{t^2}=a_{angular} Is this right?
  32. E

    How Do You Calculate Angular Velocity and Moment of Inertia?

    Hey Just trying to work out this question (see image). Solving for I (see other image) in an effort to find the angular velocity. Could someone have a look at this working and tell what I am doing right and wrong? Thanks Heaps Ed
  33. L

    Angular Acceleration.

    A circular saw blade completes 1200 revolutions in 40s while coasting to a stop after being turned off. Assuming constant deceleration, what are (a) the angular deceleration and (b) the initial angular speed? Answer in RPM/S Method I used: Change in theta is 1200 Time: 40s final Vel.:0...
  34. L

    Angular acceleration of machinery

    A piece of machinery is spinning at 760rpm . When a brake is applied, its rotation rate drops to 480rpm while it turns through 210 revolutions. What is the magnitude of the angular deceleration? Answer in Rad/s^2 Eqn I used:\omega^2=\omega_0_^2+2\alpha(change in theta) I put...
  35. T

    Angular Acceleration vs Tangential Acceleration

    Im a little fuzzy on the difference between the two. If you look at the attached picture, if that force stays with the object as it rotates, like a hand pushing in the same spot, would that force cause an angular acceleration?
  36. W

    Angular acceleration and such

    As you press down on the accelerator of your car you see the tachometer climb steadily from 1200 rpm to 5500 rpm in 2.5 s. (a) What is the angular acceleration of the car? (b) What is the tangential acceleration of a point on the edge of the engine’s 3.8 cm diameter crankshaft...
  37. R

    Two wheels and angular acceleration

    [SOLVED] Two wheels and angular acceleration Homework Statement In the figure below, wheel A of radius rA = 11 cm is coupled by belt B to wheel C of radius rC = 25 cm. The angular speed of wheel A is increased from rest at a constant rate of 1.6 rad/s2. Find the time needed for wheel C to...
  38. R

    Another angular acceleration problem. Converting radians to meters

    [SOLVED] Another angular acceleration problem. Converting radians to meters... Homework Statement A gyroscope flywheel of radius 3.13 cm is accelerated from rest at 15.0 rad/s2 until its angular speed is 2760 rev/min. (a) What is the tangential acceleration of a point on the rim of the...
  39. R

    How Do You Calculate Angular Acceleration of a Rod at a Specific Angle?

    [SOLVED] Rod...and angular acceleration Homework Statement A uniform rod AB, of length 2a and mass m, has a particle of mass 1 2m attached to B. The rod is smoothly hinged at A to a fixed point and can rotate without resistance in a vertical plane. It is released from rest with AB horizontal...
  40. T

    Weight and Wheel (Linear and Angular Acceleration)

    Weight and Wheel ! (Linear and Angular Acceleration) Homework Statement Consider a bicycle wheel that initially is not rotating. A block of mass is attached to the wheel and is allowed to fall a distance . Assume that the wheel has a moment of inertia, I, about its rotation axis...
  41. B

    Constant Angular Acceleration

    Question: A flywheel has a constant angular acceleration of 2 rad/sec^2. During the 19 sec time period from t1 to t2 the wheel rotates through an angle of 15 radians. What was the magnitude of the angular velocity of the wheel at time t1? Hint: let t1=0 sec, and t2=t Equations: \vartheta...
  42. W

    Angular Acceleration and Velocity

    Angular Acceleration and Velocity..please help :) hi could someone please explain to me conceptually what angular acceleration and angular velocity are. Also how would the angular acceleration and angular velocity of the people on a merry go round change with the location of the people...
  43. M

    Easiest Cylinder to Balance - angular acceleration

    Homework Statement 24. A person tries to balance vertically each of three long uniform cylinders with equal radii on the end of his finger: * A wood cylinder of mass m and length L with moment of inertia I * A bamboo cylinder of mass m and length 3L with moment of inertia 9I...
  44. T

    Magnitude of the angular acceleration about the pivot point?

    [SOLVED] Magnitude of the angular acceleration about the pivot point? Homework Statement A uniform horizontal rod of mass 2.7 kg and length 2.4 m is free to pivot about one end as shown. The moment of inertia of the rod about an axis perpendicular to the rod and through the center of mass...
  45. N

    Calculating Angular Acceleration of a Metal Plate

    Homework Statement A metal plate in the shape shown has a mass of 2.00kg and hangs from a pivot point located a distance d=0.300m from its center of mass. Its moment of inertia, I_cm, about an axis perpendicular to the plate and passing through the CM is 0.210kg*m2. Calculate the magnitude...
  46. K

    Angular acceleration, and revolution

    Homework Statement A car engine accerlates from 1080rpm to 4800rpm in 12.5 seconds. Calculate the angular accleration, assumed constant, and the total number of revolutions the engine makes in this time The Attempt at a Solution angular acceleration (a) = (wf - wi) /(tf - ti) (a)...
  47. B

    Rotation of a disk - find angular acceleration

    Problem: A disk rotates about its central axis starting from rest and accelerates with constant angular acceleration. At one time it is rotating at 12 rev/s; 69 revolutions later, its angular speed is 33 rev/s. Calculate (a) the angular acceleration, (b) the time required to complete the 69...
  48. I

    Angular acceleration of the disk as a function of time

    Homework Statement A disk of radius 21.0cm is free to turn about an axle perpendicular to it through its center. It has very thin but strong string wrapped around its rim, and the string is attached to a ball that is pulled tangentially away from the rim of the disk (the figure ). The pull...
  49. clope023

    Angular acceleration of a Propeller

    [SOLVED] angular acceleration of a Propeller Homework Statement An airplane propeller is rotating at 2000rev/min . \omegaz = 209rad/s How long in seconds does it take for the propeller to turn through 40degrees? Homework Equations \theta = 1/2\omegat \omegaz = d\theta/dt...
  50. J

    How Do You Calculate the Radial Component of Acceleration in a Turning Car?

    Homework Statement A car speeds up as it turns from traveling due south to heading due east. When exactly halfway around the curve, the car's acceleration is 2.70 m/s^2, 10.0 degrees north of east. What is the radial component of the acceleration at that point? Homework Equations I...
Back
Top