1. Chapter 2 Describing Motion: Kinematics In One Dimension
( Our main reference is the TEXTBOOK )

2. Reference Frames and Displacement
Kinematics deals with the description of how objects move
The description of the motion of any object must always be given relative to some particular reference frame.
Example:
A train is traveling at 80 km/h.
A person walks inside the train at a speed of 5 km/h.
5 km/h is the person’s speed with respect to the train as frame of reference.
With respect to the ground as frame of reference that person is moving at a speed of 80 km/h + 5 km/h = 85 km/h .

3. Reference Frame and coordinate axes
We will often use the model of an idealized particle or point (with no size).
A point particle can undergo only translational motion.
In Physics we often use a set of coordinate axes ,as shown in Fig. 2-3, to represent a frame of reference.
Any point(the object)on the plane can be specified by giving its x and y coordinates.
In three dimensions (chapter 3), a z axis perpendicular to the x and y axes is added.
For one dimensional motion, we often use the x axis.
If the motion is vertical, as for dropped object, we usually use the y axis.

4. Reference Frame and Displacement
A change from the object’s position x1 to the object’s position x2 is called displacement Δx.
Displacement is how far the object is from its starting point.

5. Average Velocity Average Velocity
An object’s average velocity over the time interval or elapsed time Δt= t₂ - t₁ is:
Can be negative, positive or null
SI unit : m/s
Average speed
Average speed is the distance traveled divided by the elapsed time Δt. Always positive

7. Instantaneous Velocity
The instantaneous velocity is the average velocity taken over an infinitesimally short time interval Δt → 0.

10. Acceleration Average acceleration
Is defined as the change in velocity divided by the time taken to make this change

11. Acceleration
Instantaneous acceleration
Instantaneous acceleration is defined as the limiting value of the average acceleration as Δt → 0 .

13. Motion at Constant Acceleration
We have four equations relating position, velocity, acceleration and time , when the acceleration a is constant.

15. Solving Problems

17. Freely Falling Objects