We choose the positive sense of the rotation to be counterclockwise(逆时钅 =s/r(8-1) where the s is the arc which the point P moves, and r is the radius(AP) At time ti the angular position is u, att, is 2. The angular displacement of p is Ap=p2-p during △t=t
We choose the positive sense of the rotation to be counterclockwise(逆时针). (8-1) where the s is the arc which the point P moves, and r is the radius (AP). At time the angular position is , at is . The angular displacement of P is during . 1 t 2 t 1 2 = 2 −1 2 1 t = t −t = s/r
2. Angular velocity We define the average angular velocity as (8-2) △t The instantaneous angular velocity a is △φd △→0△talt (8-3) Is aa vector quantity? The dimensions of a inverse time(t-l); its units may be radians per second rady s or revolutions per second ( rev/s)
We define the average angular velocity as (8-2) The instantaneous angular velocity is (8-3) Is a vector quantity? t av = dt d t t = = →0 lim 2. Angular velocity The dimensions of inverse time ( ); its units may be radians per second ( ) or revolutions per second ( ). −1 T rad /s rev /s