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Angular Acceleration.

  1. Jul 23, 2008 #1
    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
    Initial Vel.:?
    Alpha:? Eqn Used: (change in theta)=(1/2)(Initial vel.+final vel.)*time
    looking for inital speed:
    1200=(1/2)(initial vel+0)40seconds
    Take the vel. found and place into eqn:
    looking for alpha:
    final vel. =Initial vel.+alpha*time

    I ended up getting 1.5 ...
  2. jcsd
  3. Jul 23, 2008 #2

    Doc Al

    User Avatar

    Staff: Mentor

    This will give you the angular speed in rev/s.
    That will give you alpha in rev/s/s, not RPM/s like they want. (Convert the speed to RPM--rev/min, instead of rev/s.)
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