Table of contents

0. Math Review31m
- Math Review
  31m
1. Intro to Physics Units1h 29m
2. 1D Motion / Kinematics3h 56m
3. Vectors2h 43m
4. 2D Kinematics1h 42m
5. Projectile Motion3h 6m
6. Intro to Forces (Dynamics)3h 22m
7. Friction, Inclines, Systems2h 44m
8. Centripetal Forces & Gravitation7h 26m
9. Work & Energy1h 59m
10. Conservation of Energy2h 54m
11. Momentum & Impulse3h 40m
12. Rotational Kinematics2h 59m
13. Rotational Inertia & Energy7h 4m
14. Torque & Rotational Dynamics2h 5m
15. Rotational Equilibrium3h 39m
16. Angular Momentum3h 6m
17. Periodic Motion2h 9m
18. Waves & Sound3h 40m
19. Fluid Mechanics4h 27m
20. Heat and Temperature3h 7m
21. Kinetic Theory of Ideal Gases1h 50m
22. The First Law of Thermodynamics1h 26m
23. The Second Law of Thermodynamics3h 11m
24. Electric Force & Field; Gauss' Law3h 42m
25. Electric Potential1h 51m
26. Capacitors & Dielectrics2h 2m
27. Resistors & DC Circuits3h 8m
28. Magnetic Fields and Forces2h 23m
29. Sources of Magnetic Field2h 30m
30. Induction and Inductance3h 38m
31. Alternating Current2h 37m
32. Electromagnetic Waves2h 14m
33. Geometric Optics2h 57m
34. Wave Optics1h 15m
35. Special Relativity2h 10m

6. Intro to Forces (Dynamics)

Newton's Third Law & Action-Reaction Pairs

Physics

6. Intro to Forces (Dynamics)

Newton's Third Law & Action-Reaction Pairs

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Multiple Choice

Which of the options is NOT an action-reaction pair in the following situation? A book slides across the floor, slowing down due to friction.

Friction on the book from the floor & friction on the floor from the book

Weight of the book from the Earth & gravitational force on the Earth from the book

Weight of the book & normal force on the book

Normal force on the book from the floor & normal force on the floor from the book

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Verified step by step guidance

Identify the concept of action-reaction pairs: According to Newton's Third Law, for every action, there is an equal and opposite reaction. This means that forces always come in pairs, acting on two different objects.

Analyze the first option: 'Friction on the book from the floor & friction on the floor from the book'. These forces are indeed an action-reaction pair because the frictional force exerted by the floor on the book is matched by an equal and opposite frictional force exerted by the book on the floor.

Examine the second option: 'Weight of the book from the Earth & gravitational force on the Earth from the book'. These forces are also an action-reaction pair. The Earth exerts a gravitational force (weight) on the book, and the book exerts an equal and opposite gravitational force on the Earth.

Consider the third option: 'Weight of the book & normal force on the book'. These forces are not an action-reaction pair. The weight of the book is the gravitational force exerted by the Earth on the book, while the normal force is the support force exerted by the floor on the book. They act on the same object (the book) and are not equal and opposite forces acting on two different objects.

Review the fourth option: 'Normal force on the book from the floor & normal force on the floor from the book'. These are not an action-reaction pair. The normal force on the book is exerted by the floor, while the normal force on the floor is exerted by the book, but they are not equal and opposite forces acting on two different objects in the context of Newton's Third Law.