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.

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  1. G

    Angular acceleration of a rotating point mass

    Hi,first time posting here, so please be gentle... I am studying a point mass doing uniform circular motion on a horizontal frictionless table with tension in a string fixed at one end as the center. Everything is clear if center of circle is treated as center of rotation 'O' for the $$\tau = I...
  2. gcombina

    Is Angular Acceleration Zero in Constant Rolling Motion?

    Homework Statement Which statement concerning a wheel undergoing rolling motion is true? (a) The angular acceleration of the wheel must be zero m/s2. (b) The tangential velocity is the same for all points on the wheel. (c) The linear velocity for all points on the rim of the wheel...
  3. gcombina

    Therefore, the angular acceleration is 3.925 rad/s2.

    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 EquationsThe...
  4. R

    Angular Acceleration Equations

    According to what I've read, I was told that 1) s = r*theta 2) angle("theta"): theta(t) in radians 3) angular velocity ("omega"): omega(t) = d/dt theta(t) in rads/s 4) angular acceleration ("alpha"): alpha(t) = d/dt omega(t) in rad/(s^2) However I do not understand the concept of this. I...
  5. 2

    Can you have angular acceleration without centripetal acceleration?

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  6. K

    Angular acceleration of pulley with two masses

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  7. PhysicsStudnt

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  8. hdp12

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  9. hdp12

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  10. BrainMan

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  11. BrainMan

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  12. gcombina

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  13. BrainMan

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  14. J

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  15. P

    Angular Acceleration: 0.29 rad/s/s

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  16. V

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  17. S

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  18. R

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  19. S

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  20. J

    Calculating the angle using angular acceleration

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  21. K

    Angular Acceleration and Radius

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  22. U

    Angular acceleration of a falling arm

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  23. B

    Angular Acceleration (and other torque/angular problems)

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  24. gcombina

    Angular Acceleration Problem - Compact Disc

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  25. applestrudle

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  26. gcombina

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  27. gcombina

    Calculating Angular Acceleration for a Rotating Compact Disc

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  28. M

    Angular Acceleration and Force

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  29. U

    Angular acceleration, rigid body

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  30. AakashPandita

    Angular acceleration x radius= Acceleration of center of mass ?

    For a rotating body, (angular acceleration x radius)= Acceleration of center of mass ? But a rotating body can have angular acc. even if it is not translating. what is wrong?
  31. N

    Rotational Kinematics - Angular Acceleration

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  32. T

    Angular acceleration with a mass

    Homework Statement 1) A solid cylinder of mass M = 1.54 kg and radius r = 0.100 m pivots on a frictionless bearing. A string wrapped around the cylinder pulls downward with a force F that equals the weight of a 0.590 kg mass, i.e., F = 5.782 N. Calculate the angular acceleration of the...
  33. I

    Angular acceleration of a planet

    So my teacher said that an object farther from the center experiences greater centripetal acceleration. How is that possible? let's say we have a sun + planet system. F = GmM/r^2 so when the planet's r is greater, wouldn't the force become lower compared to the planet being closer to the sun?
  34. F

    Torque and angular acceleration

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  35. T

    Angular acceleration of an arm

    Homework Statement Assume that a 1.20-kg ball is thrown solely by the action of the forearm, which rotates about the elbow joint under the action of the triceps muscle, the figure. The ball is accelerated uniformly from rest to 9.5m/s in 0.38s , at which point it is released. Assume that the...
  36. L

    Problem with rotational torque and angular acceleration

    I've attached a screenshot of this particular question. I was able to figure out part A but I'm having some difficulty with part B. Relevant equations: T = I*alpha I = .5mr^2 (for a solid cylinder like the grinding wheel) F = ma Attempt at solution: I've gotten as far as setting up...
  37. N

    Mass on Pulley problem need to find angular acceleration

    Homework Statement A string is wrapped around a pulley of radius 3.45cm , and a weight hangs from the other end. The weight falls with a constant acceleration 3.00m/s2 . What's the angular acceleration of the pulley? Homework Equations i'm writing out the equations i would think that...
  38. A

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    Homework Statement An object travels counterclockwise on a circular path with radius R and constant angular acceleration α , so that vector r(t) = R cos(αt^2/2) i^+ R sin(αt^2/2) j^  Homework Equations b. Find the time T when the object made a single revolution and returned to...
  39. T

    Angular acceleration of a massless pulley

    Consider a massless string going over a massless frictionless pulley with masses M1 and M2 at the end of the string. The tension in the string would be same. The torque equation of the pulley says (T1-T2)=Iα .Now L.H.S is zero since T1=T2 and also I=0 . So,we have a condition 0=(0)(α)...
  40. B

    Linear and angular acceleration problems.

    Homework Statement A mass of 0.5kg is suspended from a flywheel. If the mass is released from rest and falls a distance of 0.5m in 1.5s. ( mass of wheel = 3kg, Radius = 0.3m, Radius of gyration = 212mm ). Calculate : a:The linear acceleration of the mass? b: The...
  41. N

    Angular acceleration from change in angular velocity and angle

    Is there a way to calculate angular acceleration from the change in angular velocity and the change in the angle without considering time? How would you accomplish this?
  42. joema

    Angular acceleration given force, moment arm and inertia?

    Homework Statement Find angular acceleration in deg/sec^2 given the following factors: - Total mass: 4889 kg - Moment of inertia: 4620 kg*m^2 - Moment arm length from center of mass: 1.5 meters - Force on moment arm tangent to mass: 1779 Newtons Homework Equations torque = force...
  43. S

    Help needed to convert angular velocity to angular acceleration

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  44. R

    Angular Acceleration of a Rigid Bar

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  45. S

    Calculate angular velocity and angular acceleration of a rotating mass

    I need to calculate the angular velocity of a 2kg mass rotating in a horizontal circle of 2m radius where 1 revolution takes 4 seconds ω=v/r My attempt was this : 4/360=.0111111×57.3=.636rs.
  46. U

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  47. C

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  48. Y

    Torque and Angular Acceleration for a Rigid Body Problem

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  49. M

    Archived Find the angular acceleration and velocity at the end of a rod.

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  50. N

    Find the Angular Acceleration, acceleration and friction force extered

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