PSHS 3rd Year Physics Batch 2013 Newton's Laws of Motion Vector Addition Free body diagram of box on a table

1. PSHS PHYSICS 3RD YEAR Session 2

2. The right tools to succeed in 2nd quarter physics Know TRIGONOMETRY Yes, math and physics are very much related!  Know VECTORS Know NEWTON’S LAWS Know how to make An FBD (Free Body Diagram)

3. How to master the tools? READ your physics book. ANSWER EXERCISES in the book, and verify the answers at the back of the book.

4. TRIGONOMETRY Use SOHCAHTOA Set a REFERENCE xy-plane Opposite of what? The REFERENCE ANGLE .

5. Practice!

6. VECTORS Operations on vectors Finding the resultant, given two or more vectors Finding a missing vector, given the other vectors and the resultant vector

7. Method 1: Tail-to-tip(graphical) Tip of B Tail of A

8. Method 2: Parallelogram(graphical also)

9. Tail-to-tip AND Parallelogram:Which is which? Parallelogram Tail-to-tip

10. Subtraction of vectors Given a vector A, the negative of A (or –A) is a vector of the same magnitude, but in the opposite direction

11. Subtraction of vectors

12. Method 3: Component method(computational) B = 26.5 A = 44.0 C = 31.0

13. Resolve each vector into its x- and y-components B = 26.5 A = 44.0 C = 31.0

14. Projectile Motion: The object’s motion has both x- and y-components. What is the difference between the object’s horizontal (x) component and its vertical (y) component? x-component: Uniform velocity Given: an object thrown with a horizontal velocity y-component: Accelerating downward

15. FROM YOUR DIAGNOSTIC:A projectile is fired with an initial speed of 65.2 m/s at an angle of above the horizontal on a long flat firing range. Determine: a) maximum height.

16. Formulas you should know:

17. FROM YOUR DIAGNOSTIC:A projectile is fired with an initial speed of 65.2 m/s at an angle of above the horizontal on a long flat firing range. Determine: b) total time in the air. When getting the total time, should we use the equations for the vertical or the horizontal? EITHER will do. c.) the total horizontal distance covered.

18. NEWTON’S LAWS OF MOTION

19. Newton’s First Law Law of Inertia Every object continues in its state of rest, or of uniform velocity in a straight line, as long as no net force acts on it. A school bus comes to a sudden stop, and all the backpacks on the floor start to slide forward. What force causes them to do that? NOT A FORCE. The backpacks continue their state of motion.

20. Newton’s Second Law F = ma The acceleration of an object is directly proportional to the net force acting on it, and is inversely proportional to its mass. The direction of the acceleration is in the direction of the net force acting on the object. What happens when a net force is exerted on a body/object?

21. Newton’s Third Law Action and Reaction Whenever one object exerts a force on a second object, the second exerts an equal force in the opposite direction on the first. Why does a rocket accelerate upward?

24. Exercise: A friend has given you a special gift, a box of mass 10.0 kg. The box is resting on the smooth (frictionless) horizontal surface of a table. a.) Determine the weight of the box and the normal force exerted on it by the table.

25. Exercise: A friend has given you a special gift, a box of mass 10.0 kg. The box is resting on the smooth (frictionless) horizontal surface of a table. b.) Now your friend pushes down on the box with a force of 40.0 N. What is the normal force exerted on the box by the table?

26. Exercise: A friend has given you a special gift, a box of mass 10.0 kg. The box is resting on the smooth (frictionless) horizontal surface of a table. c.) If your friend pulls upward on the box with a force of 40.0 N, what now is the normal force exerted on the box by the table?