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Homework Help: Average acceleration 2D motion

  1. Apr 23, 2009 #1
    1. The problem statement, all variables and given/known data
    Calculate the speed of the minute hand on the clock (I solved with the assumption of the minute hand being the radius) with the length of 25 cm.

    How many degrees did the minute hand move through from 12" point to 2" point?

    What is the average acceleration?

    2. Relevant equations
    a=change in V/change in time

    3. The attempt at a solution

    So i found the speed of the hand by finding circumference then divided over 3600 seconds.

    Now I need to find the angle from 12" to 2". Is it right to assume that 2" is at 45 degrees, if 3" is 90 degrees?
    Which method should I use the component or the trig method?
    please help.

    PS: is there a way to illustrate this and post it up?
  2. jcsd
  3. Apr 23, 2009 #2
    I calculated the average angular velocity to be 1.745x10^-3 rad/s

    Average acceleration will be 0, assuming that the average angular velocity is constant.

    Is this what you are after?

    there are 12 points on a clock face, so (2pi/12)*2 will give you the angle in radians between 12 and 2.

    Its 60deg :P or pi/4
  4. Apr 23, 2009 #3
    60 deg is right, but would you mind explaining it to me in a simpley way? or maybe introduce radians cuz we just skimmed over that section.
  5. Apr 23, 2009 #4
  6. Apr 23, 2009 #5
  7. Apr 23, 2009 #6
    What would happen if you cut a cake into 12 pieces and remove 2 pieces from the cake? How many degrees would the 2 pieces of cake be worth.

    360/12 = 30, 30*2=60

    Or in Radians, Pi = 180, so 2pi/12 *2 = pi/3
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