A scalar is a physical quantity that has magnitude but no direction. A vector, on the other hand, is a physical quantity that has both magnitude and direction. Operations of vectors satisfy the parallelogram rule or the triangle rule.

The range of the mass point model: 1. the size and shape of object can be ignored. 2. translating object or its all points has a same motion 3. rotation can be ignored.

Periodic natural phenomena are used to define time. The rotation of the earth, the single pendulum, the spring oscillator and the resonance rate of atoms can all be used to define time.

To determine whether an object is moving, you must first choose a frame of reference. A coordinate system is established in the reference system to accurately describe the motion of an object.

Displacement is a fundamental concept in classical physics that describes the change in position of an object. Distance is the total length of the path an object travels between its starting and ending points.

Velocity is the quantity that describes how fast or slow an object is moving. Average velocity: displacement/time interval. Average velocity: distance/time interval.

When the time interval is small, the difference between the average velocity and the instantaneous velocity is small. The instantaneous speed is equal to the magnitude of the instantaneous velocity.

Acceleration describes how fast an object changes its velocity. If the velocity and acceleration are in the same direction, the object accelerates. In the opposite direction, the object decelerates. Perpendicular, the object's velocity is constant in magnitude and changes in direction.

We explored displacement-time graphs, velocity-time graphs, and acceleration-time graphs. We also investigated the meaning of the curve slope and the area enclosed by the curve and the coordinate axes.