Motion

1. Types of motion

1.1. Oscillatory motion （摆动）

1.2. Rotational motion （转动）

1.3. Trans;lational motion （平移）

2. Scalar and vector

2.1. Scalar is quantities that only have magnitude but no direction

2.2. Vector is quantities that have a magnitude and direction

2.3. Displacement is 位移

3. Speed=distance*time

4. Mass is constant, weight change

5. moment=force*perpendicular distance between axis of rotation and line and action of force.

6. force=k*extension of spring

7. pressure=force/area of contact surface unite n/m方 or Pa(Pascal)