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Is it true or wrong that a point on a wheel rotates from 12 o’clock to 3 o’clock,...

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user1063778 | eNotes Newbie

Posted May 16, 2013 at 10:49 AM via web

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Is it true or wrong that a point on a wheel rotates from 12 o’clock to 3 o’clock, so its angular
displacement is 90 degrees? 

 

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pramodpandey | College Teacher | Valedictorian

Posted May 16, 2013 at 11:03 AM (Answer #1)

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Displacement is vector quantity and defined as change in
position.A point on a wheel rotates from 12 o’clock to 3 o’clock, so its angular displacement is 90 degrees.You can understand it as let us have a unit circle in xy plane with centre at onigine.
Circle intersect  axes at say A(1,0),B(0,1),C(-1,0), and D(0,-1).
Let move from B along circular arc in clockwise direction when reached at A ,angular position change by 90 degree because coordinate axes are mutually perpendicular.If Y axes we take initial line then X axis is perpendicular to y- axis. Thus angular displacement is 90 degree.

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pramodpandey | College Teacher | Valedictorian

Posted May 16, 2013 at 11:52 AM (Answer #2)

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Sorry ,Please include this fig for explanation.

                              y

x

                              y

x

In second graph , it shows a angular dissplacement of 90 degree from Y-axis to X-axis iyf y axis considered as initial line and movement is clockwise direction.

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