2016春八年级数学下册 小专题突破一 二次根式的化简求值技巧课件 （新版）新人教版

12/15/2016Dr. Sasho MacKenzie - HK 3768Step 4The coordinate axis should be shown on the diagram indicating positive and negative directions.NoteThe acceleration of the body will always be in the direction of force.Friction force will always oppose the direction of motion (velocity).12/15/2016Dr. Sasho MacKenzie - HK 3769The ManFx4Fx2Fy3Fy2Fy1Fx3Fy2 and Fy3 = upward ground reaction forcesFy1= body weight Fx2 and Fx3= friction forceFx4= reaction force of book on subject xy12/15/2016Dr. Sasho MacKenzie - HK 37610The BookFx4Fy1Fy2Fx2Fy2= upward table reaction forceFy1= book weight Fx2= friction forceFx4= push from instructor on book If book + accelerates Fx4 > Fx2If book - accelerates Fx4 < Fx2Zero acceleration Fx4 = Fx2xy