KINEMATICS LESSON 1 Part 1

Title: Kinematics

Introduction

• Kinematics is a branch of mechanics in physics focused on the motion of objects without considering forces that produce the motion.

Understanding Motion

• Definition: Motion is the change in position of an object over time with respect to a reference point.

• Objects are in motion if they change position relative to a fixed object (e.g., a tree).

Frame of Reference

• Definition: A frame of reference is the viewpoint of the observer of motion, allowing specification of the location of objects.

• Example: A passenger in a moving train is stationary with respect to the train but is moving with respect to the ground.

  • When seated, the passenger observes no movement relative to the train but is moving relative to the railroad.

Examples of Motion

• Passenger searching for a seat in a moving train.

• Another example: Dribbling a ball on a table inside the moving train as an observer.

• Changes in frames of reference can modify how motion is perceived, such as observing from within the train versus outside.

Distance vs. Displacement

Distance

• Definition: The length of the actual path traveled by an object.

• Example: If a chalk piece travels from point A to point B (1.5 m), returning from B to A adds to the total distance covered.

Displacement

• Definition: Length and direction of the change in position measured from the starting point.

• Example: For a displacement of 1.5 m east or along the positive x-axis, the direction is key to determining displacement.

Exercises

• Exercise 1: A group of climbers walked 10.0 km north and then 20.0 km east.

  • a. Total distance: 30.0 km.

  • b. Total displacement needs calculation using the Pythagorean theorem for the resultant.

• Exercise 2: Walking 1.0 km north, 2.0 km east, then 4.0 km west, and 7.0 km back to the starting point.

  • a. Calculate total distance covered.

  • b. Calculate total displacement, noting the net movement results in zero displacement back to starting point.

Conclusion

• Understanding kinematics and the concepts of motion, frame of reference, distance, and displacement is crucial for solving physical phenomena in science.