Angular acceleration Definition and 566 Threads

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.

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  1. George_J

    Torque & Inertia calculation for a wheel

    Hello! Before I start I want to apologize for my english and not having a scanner (lol). I'm calculating the torque needed to rotate a wheel* around its own axis from above, ( see the link at the end of post). I have quite an good idea to how I'm supposed to calculate it but I feel that...
  2. jdawg

    What Are the Angular Velocity and Acceleration in This Mechanism?

    Homework Statement Block D of the mechanism is confined to move within the slot of member CB . Link AD is rotating at a constant rate of ωAD = 4 rad/s measured counterclockwise. Suppose that a = 350 mm , b = 200 mm. Find wCB and αCD Homework EquationsThe Attempt at a Solution [/B] I hope its...
  3. RoboNerd

    Angular Acceleration and Moment Arm

    Homework Statement [A rocket has landed on Planet X, which has half the radius of Earth. An astronaut onboard the rocket weighs twice as much on Planet X as on Earth. If the escape velocity for the rocket taking off from Earth is v , then its escape velocity on Planet X is a) 2 v b) (√2)v c) v...
  4. R

    Angular acceleration from angular velocity

    Hello everybody. I would really appreciate some help Homework Statement I have some problem where I have measured angular velocity data. This measurements are not equally spaced, meaning there were taken after some (variable) delay passed. I need to find what is the angular acceleration at...
  5. SoNiiC

    Slipping Ladder Angular Acceleration

    Homework Statement The following problem is part of a physics lab with unclear directions. The lab prompt says: Find the angular acceleration of a meterstick as it slips down a wall. Here is my interpretation of the lab: A meterstick of mass 0.15kg is leaning against the wall. At an angle of...
  6. K

    Angular acceleration, tangential acceleration

    Homework Statement Two go-karts race around a course that has concentric circular tracks. The radius of the inner track is 15.0 m, and the radius of the outer track is 19.0 m. The go-karts start from rest at the same angular position and time, and move at the same constant angular acceleration...
  7. RoboNerd

    Why Does the Solution Use (T2 - T1) * R for Net Torque?

    Homework Statement https://web.njit.edu/~gary/111/assets/HW10_SOL.pdf'][/PLAIN] https://web.njit.edu/~gary/111/assets/HW10_SOL.pdf The problem is on page 3 of the document along with relevant solutions. Homework Equations F=ma, and Sigma Torques = (moment of inertia) * angular acceleration...
  8. T

    Find the time for the string to break

    Hi all! I am currently working on an assignment for my dynamics course in which we need to create our own "real world" problems. I chose to do a problem which would solve the time at which the string of a lanyard would break when it is swung in a circle. My problem is with my end numbers. They...
  9. S

    Working out the angular acceleration of a flywheel

    I am trying to work out the angular acceleration of a small flywheel (with axle running through) when an attached piston (by means of a pin) with an outstroke force acts on it. I assumed I would need to work out the torque using the formula torque = force x radius, and find out the flywheel’s...
  10. A

    How to calculate angular acceleration of crankshaft?

    Hello. I am currently undergoing a university project and require the angular acceleration of a crankshaft? I only know the angular velocity from the RPM and I have strongly considered that it is not possible. Just looking for some reassurance? Cheers
  11. S

    Rotational Inertia, Torque and Angular Acceleration (1Q)

    Homework Statement . What is the angular acceleration if a force of 3 N is applied perpendicular to the radius of a 5 kg solid sphere that has a radius of 0.6 meters? Homework Equations = r x F I = mr^2 The Attempt at a Solution I used tried solving for angular acce. 3N/(5kg)(0.6)...
  12. x2017

    Find the average angular acceleration of the sprinter

    Homework Statement A sprinter runs the curve of this 200 m in 11.61 s. Assume he ran in a lane which makes a semicircle (r = 32.4 m) for the first part of the race. At 3.59 s into the race his speed is 5.9 m/s. At 7.9 s into the race his speed is 8.4 m/s. His speed after the curve was 12.4 m/s...
  13. J

    Angular Acc. Homework: Calculate Centripetal & Angular Acc.

    Homework Statement An airplane makes a circular turn of radius 9 km at a constant speed of 650 km/h. Calculate the magnitude of the plane's a. angular velocity, b. centripetal acceleration, c. angular acceleration, d. tangential acceleration Homework Equations w = v/r aR = w^2r The Attempt at...
  14. REVIANNA

    Variable angular acceleration and velocity

    Homework Statement This is a general query not a specific problem. In several questions in rotational dynamics they ask the trend in angular acceleration and angular velocity.In one of them they released a rod from horizontal position and asked if the angular velocity and angular acceleration...
  15. dwinsemius

    Coin rolling on another coin, when will free fall occur?

    Homework Statement Doing this from a memory of a final exam question from freshman physics that I could not solve 45+ years ago. A coin of radius R is poised at the top of another (fixed) coin of radius 2R. If it rolls with no slip, at what point will the top coin leave the lower coin. (I...
  16. dumbdumNotSmart

    Angular acceleration in moment of inertia

    I'm having a hard time undertanding a concept of moment of inertia and Angular acceleration. Homework Statement We have a closed system above. M1 is a cylinder of 2 Kilograms, moment of inertia of a cylinder ( MR2 /2 ) with a string tightly rolled around it. This string connects to a free...
  17. droidofthevoid

    Total acceleration from angular acceleration

    Homework Statement A discus thrower ( with arm length of 1.2 m) starts from rest and begins to rotate counterclockwise with a constant angular acceleration of 2.5 [rad/s^2]. What is the magnitude of the total acceleration of the discus when its angular velocity is 9.0[rad/s]? Homework...
  18. vetgirl1990

    Finding angular acceleration of pulley attached to a mass

    Homework Statement A block of mass 2kg (mb) can slide down a frictionless 53 degree inclune, but it is connected to a pulley of mass 4kg (mp with a radius of 0.5m. The pulley may be treated as a disk. What is the angular acceleration of the pulley? Homework Equations a = rα The Attempt at a...
  19. D

    What is the relationship between tangential and radial acceleration?

    Homework Statement Homework Equations αt = r α The Attempt at a Solution ωi = 0 rad/s αt = 2.00 rad/s2 r = 112 m θ = ? at a = 6.80 m/s2 I'm not exactly sure where to begin. Help is appreciated.
  20. 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...
  21. H

    Angular acceleration, velocity, momentum of a door?

    1. Homework Statement A door of width l = 1.00 m and mass M = 15.0 kg is attached to a door frame by two hinges. For this problem, you may ignore gravity, as we are interested in rotational motion around the vertical axis. There is no friction of any kind. An angry mother-in-law slams the...
  22. H

    Calculating Angular Acceleration and Torque in a Rotating Motor System

    Homework Statement The rotating subunits forms an approximately cylindrical axel with a diameter of 4 nm and total mass of 80,000 Daltons. The motor takes three steps per revolution with each step taking 0.067 s. We can model the rotating subunits as a rotating cylinder and use the properties...
  23. K

    Angular acceleration at the bottom

    Homework Statement You hold a small ice cube near the top edge of a hemispherical bowl of radius 100 mm. You release the cube from rest. What is the magnitude of its acceleration at the instant it reaches the bottom of the bowl? Ignore friction. Homework Equations a=v^2/r delta U= delta Krot...
  24. K

    Maximizing Angular Acceleration

    Homework Statement A massless stick of length d, held parallel to the ground, has a mass, m, attached at one end of it and a pivot on the other end. A second mass, m, is glued on at a distance x from the pivot. At what distance x would maximize the angular acceleration of the stick the instant...
  25. dumbdumNotSmart

    Angular acceleration for one gear to another

    Homework Statement Gear r has angular acceleration of a magnitude of .2 rads^{-2}(counterclockwise) and is resting at t=0s . p is a cylinder welded to R (concentric). r applies torque to R, these do not slip or slide. A mass m hangs from a string which is attached to p. This string is not...
  26. B

    Angular acceleration of a tire....not sure how to find radius

    Homework Statement :[/B] Your car tire is rotating at 3.5 rev/s when suddenly you press down hard on the accelerator. After traveling 200 m, the tire’s rotation has increased to 6.0 rev/s. What was the tire’s angular acceleration? Give your answer in rad/s2. Homework Equations :[/B]...
  27. L

    Find the angular acceleration of the rod

    Homework Statement Given: ##\mu_B=0.52## ##\theta=30^{\circ}## Weight- ##25## lb ##\omega=0## ## l=6## ft ##r_c=3\sqrt 2## radius of curvature. Homework Equations My Equations of motion are the following: ##\xleftarrow{+}\sum F_x=N_A\sin 60 - F_B=0## ##\downarrow{+} \sum F_y= N_A \cos...
  28. UMath1

    Bicycle Translational Acceleration vs Angular Acceleration

    Homework Statement Given: Wheel radius is 20 CM, Gear radius is 5 CM, Coefficient of Static Friction is .2, Weight on rear wheel is 50 N. What is the minimum force that must be applied to the pedal for the wheel to begin accelerating on a level surface?Homework Equations Net T = I * a T = R X...
  29. D

    ANSYS Workbench - Insert Angular Acceleration

    Hello, I am setting up a model in ANSYS Workbench Mechanical and I would like to insert an certain angular acceleration. How can I do it? Thanks a lot!
  30. M

    Ttorque angular acceleration units check

    Given : A (hypothetical) wheel with a m.o.i. of 1 lb*ft^2 Radius of wheel = 1.9099 inches, therefore circumference of wheel = 1 foot The wheel is at rest, i.e. zero rotation speed. A torque of 1 ft/lb is applied for 1 second Is the result a rotation of 1 r.p.s. (60 r.p.m.) ? thx Mike
  31. C

    Force, linear and angular acceleration, car & wheels help

    I'm building an excel dragstrip model. I already have a working model that incorporates force exerted at the rear tires, force of drag, and force of rolling resistance. Now, I want to take into account the linear force that acts on the front tires that is required to accelerate them. There is...
  32. DameLight

    Rotational ACC and Gravitational ACC

    solved thank you : ) 1. Homework Statement A bucket of water of mass 14.2 kg is suspended by a rope wrapped around a windlass, that is a solid cylinder with diameter 0.350 m with mass 12.8 kg . The cylinder pivots on a frictionless axle through its center. The bucket is released from rest at...
  33. kostoglotov

    Answer out by 2 orders of magnitude....how?

    Homework Statement A tradesman sharpens a knife by pushing it against a grindstone with a given applied force. The grindstone is 28kg, 15 cm in radius, is originally going at 200 rpm but is slowed down to 180 rpm over 10 s by applying the knife. The coefficient of kinetic friction is 0.20...
  34. kostoglotov

    Net angular acceleration of a two wheel system

    Homework Statement The problem Direct imgur link to problem: http://i.imgur.com/QCc0zj6.jpg Homework Equations \alpha = \frac{\tau_{net}}{I} I = \frac{1}{2}MR^2 \tau = rF = rmg The Attempt at a Solution I have figured that the moment of inertia of the entire system must be used for...
  35. Y

    Angular Velocity and Acceleration for Elevator Mechanism

    Homework Statement In a charming 19th-century hotel, an old-style elevator is connected to a counterweight by a cable that passes over a rotating disk 3.50m in diameter (the figure (Figure 1) ). The elevator is raised and lowered by turning the disk, and the cable does not slip on the rim of...
  36. S

    Two Weighted Pulleys with a Suspended Mass

    Homework Statement Consider a uniform 10-kg circular disk with diameter .4m. The disk is free to rotate about a horizontal axis through its center. A (massless) cord wrapped around the disk passes over a 2-kg pulley, P, with diameter .2m and is attached to a 25-kg mass. The pulley's mass...
  37. Prashant91

    Angular motion-centrifuge problem .

    Homework Statement : A centrifuge starts from rest and speeds up at 3400rpm after 50 seconds. a sample is at a distance of 37.5mm from the centre 1) find the angular acceleration 2) calculate the centripetal acceleration [/B] Homework Equations : v2 / r v = rω a = rω2 a=Λω/Λt 3. The...
  38. H

    What Is the Angular Acceleration of a Released Uniform Plate?

    Homework Statement A uniform plate of mass m is suspended as shown.What will be the angular acceleration immediately after connection at B has been released? http://i.stack.imgur.com/1hMuk.png 2. My attempt- I used torque=M.I*angular acceleration I chose the axis to be perpendicular to the...
  39. H

    Angular acceleration of a rigid rod with a mass at both ends

    1. A rigid rod of mass M and length L rotates in a vertical plane about a frictionless pivot through its center of mass. Particles of masses m1 and m2 are attached at the ends of the rod. Determine the angular acceleration of the system when the rod makes an angle θ with the horizontal. In the...
  40. M

    A cuboid on an inclined plane - based on an Olympiad problem

    Homework Statement Let's suppose we have a [cuboid](http://en.wikipedia.org/wiki/Cuboid) of dimensions ##a \times b \times c##. We put it on an inclined plane of an angle ##\alpha## so that only one edge of length ##c ## touches the plane. In time ##t = 0 ## the cuboid doesn't rotate. Let the...
  41. S

    How Do You Calculate Angular Acceleration of a Salad Spinner?

    Homework Statement Dario, a prep cook at an Italian restaurant, spins a salad spinner 20.0 times in 5.00 seconds and then stops spinning it. The salad spinner rotates 6.00 more times before it comes to rest. Assume that the spinner slows down with constant angular acceleration. What is the...
  42. N

    Solving Turntable Coin Problem: Angular & Linear Accelerations

    A very small coin is at distance 10.5 cm from the spindle of a turntable. The turntable starts spinning from rest with constant angular acceleration. In 0.133 s the coin's centripetal acceleration is 1.39 times its tangential acceleration. 1)Find the turntable's angular acceleration. 2)Find the...
  43. M

    Finding resultant velocity from angular acceleration

    Homework Statement Michael starts spinning the rope at a rate of 2.00 rad/s^2 while he starts running towards the target at 4.00m/s^2. This distance betweens Michael's elbow and the end of the rope form a straight 1.2m segment. If Michael takes 3 seconds before he launches the rope at the...
  44. T

    Find angular acceleration using theoretical values

    Homework Statement I'm doing a coursework where I must find the angular acceleration of a rolling tin can using theoretical values. I have its mass and radius. I actually have experimental data so i have access to the actual values of angular velocity and angular acceleration, as well as time...
  45. R

    Trajectory of a turning particle

    In this problem, I need to find the trajectory of a particle (as a function of time) which moves at a speed 's' but also turns at an increasing rate; angular acceleration α. The trajectory looks like a spiral which converges to a point. The particle has an initial position vector p and a...
  46. A

    Calculating angular acceleration of a wire

    Homework Statement A rigid uniform horizontal wire PQ of mass M, pivoted at P, carries a constant current I. It rotates with a constant angular speed in a uniform vertical magnetic field B. If the current were switched off, the angular acceleration of the wire in terms of B, M and I would be...
  47. S

    Angular acceleration of a yo-yo pulled with constant force

    Homework Statement A yo-yo is pulled with a constant tension T. The string is horizontal and parallel to the table and unwinding from the bottom of the spool, as shown. The yo-yo's outer radius is R and the spool radius is r. The mass of the yo-yo is m and the moment of inertia of the yo-yo...
  48. gcombina

    Angular Acceleration (Grindstone Problem)

    Homework Statement A grindstone, initially at rest, is given a constant angular acceleration so that it makes 20.0 rev in the first 8.00 s. What is its angular acceleration? (a) 0.313 rad/s2 (c) 2.50 rad/s2 (e) 3.93 rad/s2 (b) 0.625 rad/s2 (d) 1.97 rad/s2Homework Equations...
  49. B

    Angular Acceleration of a Wheel on a Turntable

    Homework Statement [/B] The axle of a wheel is mounted on supports that rest on a rotating turntable. the wheel has angular velocity ##\omega_1 = 44.0\; \frac{\textrm{rad}}{\textrm{s}}## about its axle, and the turntable has angular velocity ##\omega_2 = 35.0\; \frac{\textrm{rad}}{\textrm{s}}##...
  50. A

    Torque v. Time Graph -- Find angular velocity

    Homework Statement An object whose moment of inertia is 3.00kgm2experiences the torque shown in the figure (Figure 1) . What is the object's angular velocity at 2.80s ? Assume it starts from rest. http://session.masteringphysics.com/problemAsset/1073771/4/knight_Figure_13_21.jpg Homework...
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