1. 5 Newton’s Third Law of Motion
Force as an interaction
Newton’s 3rd Law
Systems
Vectors and Vector Components

2. Forces and Interactions
inter = between
all forces are interactions between masses
each mass feels same size force

3. What forces act on the man? Draw a Force Diagram for him.

4. Newton’s 3rd Law of Motion
Whenever one object exerts a force on a second object, the second object exerts an equal and oppositely directed force on the first.

5. Force-Pairs in Action

6. Systems
forces external to the system determine the systems acceleration
systems are defined so unknown forces can be determined, e.g., tension can be determined below

7. What external forces act on this system?

8. Action and Reaction

9. Summary of Newton’s Laws
First: Law of Inertia
Second: Fnet = ma
Third: Forces occur in pairs (equal size, opposite direction)

10. Force Diagram each object. Which has greater acceleration when released?

11. Page 21, 22 in Practicing Physics!!!

12. Vectors magnitude and direction represented by arrows
examples: force, velocity, and displacement
added to determine net force
addition is done tail-to-head
applies to velocity

13. Net Force as Vector Addition

14. Diagonal of Square is 1.41 times its sides

16. Which Plane has Highest Ground Speed?

17. Components of Vectors component = part
horizontal part is the “x component”
vertical part is the “y component”

18. Which strings have greater tension?

20. Practical Vector Addition

21. Another Use of Components

22. Summary All forces are interactions, i.e., part of a pair of forces
Newton’s 3rd Law: pairs have equal size opposite direction
Systems are defined to determine unknown forces
Vectors, Vector Components, Parallelogram Rule

23. Practicing physics Do Page 27
Refer to page 26 to review parallelogram rule of vector addition