(3)Translation and Rotation at same time Often a rigid body can simultaneously(同时) have two kinds of motions 平动和转动(轴动)
Often a rigid body can simultaneously(同时） have two kinds of motions. (3) Translation and Rotation at same time 平动和转动（轴动）
定轴转动 平动和转动(转轴位置变)
平动和转动（转轴位置变） 定轴转动
3. Rotation of a rigid body around a fixed axis 刚体的定轴转动 Example: A rotation around a fixed axis Every point of the rigid body moves in a circle(刚体上各点都 作圆周运动 轴
3. Rotation of a rigid body around a fixed axis 刚体的定轴转动 Example: A rotation around a fixed axis 轴 Every point of the rigid body moves in a circle(刚体上各点都 作圆周运 动)
All the points in the rigid body: To rotate around an axis Circular motion with different radii (刚体上各点都绕同一转轴作不同半 径的圆周运动) Q 轴
（ 刚体上各点都绕同一转轴作不同半 径的圆周运动) P Q 轴 All the points in the rigid body: • Circular motion with different radii. •To rotate around an axis
(1)Characteristic: all points have the same angular displacement, angular speed angular acceleration △,,B 特点 各质点均在垂直转轴的 平面内作圆周运动且角 ■■■■■■ 位移,角速度和角加速 Q 度均相同。 轴
（1）Characteristic: all points have the same angular displacement, angular speed & angular acceleration. 特点： 各质点均在垂直转轴的 平面内作圆周运动且角 位移，角速度和角加速 度均相同。 P Q 轴 ,,