LESSON 4-INERTIAL FRAME OF REFERENCES-ACTIONREACTION-FREE BODY DIAGRAM.pptx

INTRODUCTION TO DYNAMICS

1. Inertial Reference Frames, Action-Reaction Pairs, and Free Body Diagrams LESSON 4:

2. Introduction to Inertial Reference Frames An inertial reference frame is a frame of reference in which an object remains at rest or in uniform motion unless acted upon by a force. These frames follow Newton's First Law of Motion. Examples: A car moving at constant speed, a stationary train.

3. Characteristics of Inertial Reference Frames No acceleration present. Observers in these frames see objects obeying Newton's laws. Essential for simplifying the analysis of motion.

4. Non-Inertial Reference Frames Frames that are accelerating or rotating. Pseudo-forces appear in these frames (e.g., centrifugal force). Examples: A car accelerating, a rotating merry-go-round.

5. Newton's Third Law of Motion For every action, there is an equal and opposite reaction. Forces always come in pairs. Examples: Pushing against a wall, walking on the ground.

6. Understanding Action-Reaction Pairs Action and reaction forces act on different objects. They are equal in magnitude but opposite in direction. Example: A book on a table (book pushes down, table pushes up).

7. Examples of Action-Reaction Pairs Jumping off a boat (you push the boat, the boat pushes you). Rocket propulsion (exhaust gases push back, rocket moves forward). Swimming (hands push water back, water pushes you forward).

8. Introduction to Free Body Diagrams A graphical representation of forces acting on an object. Helps in analyzing the motion of the object. Simplifies complex problems by isolating the object of interest.

9. Components of Free Body Diagrams Object represented by a dot or a simple shape. Arrows represent forces acting on the object. Each arrow is labeled with the type and magnitude of the force.

10. Steps to Draw a Free Body Diagram Identify the object of interest. Draw the object as a dot or simple shape. Draw and label all forces acting on the object. Include gravitational, normal, frictional, and applied forces.

11. Example: Free Body Diagram of a Book on a Table Object: Book Forces: Weight (downward), Normal force (upward) Arrows: Equal length, opposite directions Labels: W (weight), N (normal force)

12. Example: Free Body Diagram of a Sliding Box Object: Box Forces: Weight (downward), Normal force (upward), Friction (opposite to motion), Applied force (direction of motion) Arrows: Proportional to force magnitudes Labels: W, N, F friction , F applied

13. Analyzing Forces in Free Body Diagrams Sum of forces determines the net force. Net force determines acceleration (Newton's Second Law). Helps in solving for unknown forces or accelerations.

14. Common Mistakes in Free Body Diagrams Forgetting to include all forces. Incorrectly labeling forces. Misrepresenting the direction or magnitude of forces.

15. Practice Problem: Free Body Diagram of a Hanging Lamp Object: Lamp Forces: Weight (downward), Tension in the string (upward) Draw and label the forces. Determine if the forces are balanced.

16. Practice Problem: Free Body Diagram of a Car on a Hill Object: Car Forces: Weight (downward), Normal force (perpendicular to hill), Friction (opposite to motion), Applied force (uphill) Draw and label the forces. Analyze the net force and motion.

17. Real-World Applications of Free Body Diagrams Engineering: Designing structures and vehicles. Physics: Understanding motion and forces. Everyday life: Analyzing simple machines and tools.