Newton's Laws of Motion
Newton's laws of motion are three fundamental principles that describe the relationship between the motion of an object and the forces acting on it. These laws form the foundation of classical mechanics.
1. First Law (Law of Inertia)
An object at rest remains at rest, and an object in motion continues in motion with constant velocity unless acted upon by a net external force.
2. Second Law (Law of Acceleration)
The acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. Mathematically,
$$ \vec{F} = m\vec{a} $$
where $\vec{F}$ is the net force, $m$ is the mass, and $\vec{a}$ is the acceleration.
3. Third Law (Action-Reaction Law)
For every action, there is an equal and opposite reaction. If object A exerts a force on object B, then object B exerts a force of equal magnitude and opposite direction on object A.
Worked Example
Problem:
A $2,text{kg}$ object experiences a net force of $10,text{N}$ \to the right. What is its acceleration?
**Solution:**
By Newton's second law:
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Substitute the given values:
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Solve for $a$:
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**Answer:**
The acceleration is $5,text{m/s}^2$ \to the right.
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## Takeaways
- Newton's laws explain how forces affect the motion of objects.
- The second law provides a quantitative relationship: $F = ma$.
- Action and reaction forces are always equal in magnitude and opposite in direction.