Newton's Third Law

• What does Newton's Third Law deal with?

  Forces involved when two objects interact
• What does Newton's Third Law state about forces between two objects?

  They are equal in magnitude and opposite in direction
• What are third-law pairs?

  Forces that arise in pairs during interaction
• What are the requirements for a Newton's third law force pair?

  • Same type of force
  • Same magnitude
  • Opposite in direction
  • Acting on different objects
• How does Newton's Third Law explain walking?

  The foot pushes the ground backwards
• What happens when the foot pushes on the ground?

  The ground pushes back on the foot
• What are the forces involved when walking called?

  Normal contact forces
• What is the relationship between the magnitudes of the forces when walking?

  Both forces are of equal magnitude
• Why is it a common error to misidentify forces in a third law situation?

  People confuse normal force with weight
• What must be considered to apply Newton's Third Law correctly?

  The interaction between two objects
• What is the first law of motion according to Newton?

  Objects remain at rest unless acted on
• What is the significance of the free-body force diagram in this context?

  It shows multiple forces on one object
• What must be true for forces to be considered a Newton's third law pair?

  They must be the same type of force
• What happens when the book pushes on the table?

  The table pushes back on the book
• What are the forces between the book and the Earth called?

  Weight forces

  
• What is the gravitational pull of the Earth on the book?

  The weight of the book
• Why can't two equal forces in opposite directions be assumed to be third law pairs?

  They must meet all specific criteria
• What is Newton's first law of motion?

  Objects will remain at rest unless acted on
• What is Newton's second law of motion?

  Force equals mass times acceleration