1. Newton’s 2 nd Law: More Practice

4. Newton’s 3 rd Law: Student Learning Goals The student will be able to state Newton’s 3 rd Law and apply it in qualitative and quantitative terms to explain the effect of forces acting on objects. (B3.4)

5. Newton’s 3 rd Law SPH4C

6. Newton’s 3 rd Law of Motion “For every action, there is an equal and opposite reaction.”

7. Newton’s 3 rd Law of Motion “For every action, there is an equal and opposite reaction.” More accurately: for every action force on object B due to object A, there is a reaction force, equal in magnitude but opposite in direction, on object A due to object B.

8. Newton’s 3 rd Law of Motion What does this mean in practice? Examples: An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force?

9. Newton’s 3 rd Law of Motion What does this mean in practice? Examples: An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? The Earth experiences a gravitational force of 15 N [up].

10. Newton’s 3 rd Law of Motion What does this mean in practice? Examples: An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? The Earth experiences a gravitational force of 15 N [up]. The same object resting on a table experiences a normal force of 15 N [up]. What is the reaction force? The same object resting on a table experiences a normal force of 15 N [up]. What is the reaction force?

11. Newton’s 3 rd Law of Motion What does this mean in practice? Examples: An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? An object near the Earth’s surface experiences a gravitational force of 15 N [down]. What is the reaction force? The Earth experiences a gravitational force of 15 N [up]. The same object resting on a table experiences a normal force of 15 N [up]. What is the reaction force? The same object resting on a table experiences a normal force of 15 N [up]. What is the reaction force? The 15 N [down] normal force on the table.

12. Newton’s 3 rd Law in Practice A 55 kg person standing on a frictionless ice rink throws a 5.0 kg ball with a force of 25 N [E]. What is the acceleration of the: (a) ball; (b) person?

13. Newton’s 3 rd Law in Practice A 55 kg person standing on a frictionless ice rink throws a 5.0 kg ball with a force of 25 N [E]. What is the acceleration of the: (a) ball; (b) person? The acceleration of the ball is:

14. Newton’s 3 rd Law in Practice A 55 kg person standing on a frictionless ice rink throws a 5.0 kg ball with a force of 25 N [E]. What is the acceleration of the: (a) ball; (b) person? The acceleration of the person is:

15. More Practice Hands On with Newton’s 3 rd Law