3. The rotating vector representation(旋转矢量 表示法) of shM A vector A with a length A is rotating about point o at an angular velocity o in Fig. 15-4. t=0 Fig 15-4
3. The rotating vector representation(旋转矢量 表示法） of SHM A vector with a length A is rotating about point o at an angular velocity in Fig.15-4. A t = 0 Fig.− t +
The projection P of this rotating vector in X-axis is a+pt=0 given by x= Acos at +p) Fio.15-4 which is as same as the equation of shM. A rotating vector: one to one SHM 一一对应
The projection P of this rotating vector in x-axis is given by x = Acos(t + ) which is as same as the equation of SHM. A rotating vector one to one 一一对应 SHM t = 0 Fig.− t + x
4. Remarks. A simple harmonic oscillator has to have two parts: (1)Spring which provides a restoring E force( that is it store the potential energy); NAXXXXXXXXXn (2)‘ Body' which 平衡位置 has inertia( that is it store the kinetic energy). E K
4. Remarks: A simple harmonic oscillator has to have two parts: (1)‘Spring’ which provides a restoring force( that is it store the potential energy); (2) ‘Body’ which has inertia( that is it store the kinetic energy). k EP m EK
§14-2 Amplitude(振幅) Period(周期) Frequency (頻率) and phase(位相) of shm 1Introduction km氵x From x=:Acos( @: 0 平衡位置 Fig.15-1 8 We can see that (1) The displacement is determined by th ree quantities: A, 0, (P; (2 )Acos(at +o) is a periodic function of tim
§14-2 Amplitude (振幅) Period (周期) Frequency (頻率) and Phase (位相) of SHM 1.Introduction From x = Acos(t + ) We can see that: (1) The displacement is determined by three quantities: A, , ; (2) is a periodic function of time t. Acos(t +) k m x Fig.15 −1