Newton's Third Law Calculator
For every action, there is an equal and opposite reaction - Calculate action-reaction force pairs
Newton's Third Law Calculator
Mass of the first object applying the action force
Acceleration of the first object (can be negative)
Mass of the second object experiencing the reaction force
Newton's Third Law Results
Newton's Third Law: F_action = -F_reaction
Applied formula: m₁ × a₁ = -(m₂ × a₂)
Force magnitude: 0.00 N
Example Calculation
Collision Between Two Objects
Given: Object A (90 kg) accelerates at 20 m/s² to the right
Find: Acceleration of Object B (30 kg) during collision
Solution
Using Newton's Third Law: m₁ × a₁ = -(m₂ × a₂)
90 kg × 20 m/s² = -(30 kg × a₂)
1800 N = -(30 kg × a₂)
a₂ = -1800 N / 30 kg = -60 m/s²
Result: Object B accelerates at 60 m/s² to the left
Newton's Three Laws
First Law
Objects at rest stay at rest; objects in motion stay in motion
Law of Inertia
Second Law
F = ma
Force equals mass times acceleration
Third Law
For every action, there is an equal and opposite reaction
Action-Reaction Pairs
Real-world Applications
Understanding Newton's Third Law
What is Newton's Third Law?
Newton's Third Law states that "for every action, there is an equal and opposite reaction." This means that forces always come in pairs. When one object exerts a force on another object, the second object simultaneously exerts a force of equal magnitude but in the opposite direction on the first object.
Key Principles
- •Forces always occur in pairs (action-reaction pairs)
- •Action and reaction forces are equal in magnitude
- •Action and reaction forces are opposite in direction
- •Forces act on different objects
Mathematical Formulation
F_action = -F_reaction
m₁a₁ = -(m₂a₂)
- F_action: Force exerted by object 1 on object 2
- F_reaction: Force exerted by object 2 on object 1
- m₁, m₂: Masses of the two objects
- a₁, a₂: Accelerations of the two objects
Important: The negative sign indicates that the forces are in opposite directions. The forces act on different objects, so they don't cancel each other out.
Why Don't Action-Reaction Forces Cancel Out?
A common misconception is that action-reaction forces cancel each other out. They don't because:
They Act on Different Objects
Action force acts on object B, while reaction force acts on object A. Since they act on different objects, they cannot cancel each other out.
Different Reference Frames
Each force affects the motion of its respective object. The net force on each object depends on all forces acting on that specific object, not forces it exerts on others.