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state-newtons-third-law-of-motion

🚀 Newton's Third Law of Motion states that for every action, there is an equal and opposite reaction. This means that whenever one object exerts a force on another object, the second object exerts a force of equal magnitude but in the opposite direction on the first object. This law is fundamental in understanding how forces interact in our universe and is crucial for analyzing motion and dynamics in physics.

Theory Explanation

Understanding Action and Reaction Forces

When an object A exerts a force on object B, object B simultaneously exerts a force on object A. These forces are equal in magnitude and opposite in direction. This is the essence of Newton's Third Law of Motion.

\[ F_{AB} = -F_{BA} \]
Impulse and Its Relation to Forces

Impulse is defined as the change in momentum of an object when a force is applied over a period of time. It is given by the formula Impulse = Force × Time. According to Newton's Third Law, the impulse experienced by two interacting objects will be equal and opposite.

\[ J = F \Delta t \]

Key Points

  • 🎯 For every action, there is an equal and opposite reaction.
  • 🎯 Action and reaction forces act on different objects, not on the same object.
  • 🎯 Impulse is the product of force and the time duration over which it acts.
  • 🎯 Understanding these concepts is crucial for solving problems in dynamics and mechanics.
  • 🎯 These laws apply universally, regardless of the scale of the objects involved.

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Examples:💡

A person standing on a skateboard pushes against a wall. What happens to the skateboard?

Solution:

Step 1: When the person pushes against the wall, they exert a force on the wall.

\[ F_{person-wall} = F_{wall-person} \]

Step 2: According to Newton's Third Law, the wall exerts an equal and opposite force on the person.

\[ F_{wall-person} = -F_{person-wall} \]

Step 3: As a result of the force exerted by the wall, the skateboard moves in the opposite direction of the push.

Common Mistakes

  • Mistake: Students often think that action and reaction forces cancel each other out, leading to no motion.

    Correction: Action and reaction forces act on different objects, so they do not cancel each other out. They can cause motion in the system.

  • Mistake: Confusing impulse with momentum; students may think they are the same.

    Correction: Impulse is the change in momentum, not momentum itself. Remember that impulse = Force × Time.

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