Law of Conservation of momentum & Angular momentum

 

Physics is filled with powerful laws that work quietly behind the scenes, ensuring the universe behaves predictably. Two such hidden heroes are the conservation of momentum and conservation of angular momentum. They’re not just abstract rules — they explain everything from how rockets launch to why a spinning skater twirls faster with arms pulled in.

What Is Momentum?

Momentum is the “oomph” an object has when it’s moving — a combination of its mass and velocity.

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$$\text{<span style="color: \#cc0000; font-family: helvetica;"><b>Momentum (p) = mass (m) × velocity (v) </b></span>}$$

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The Law of Conservation of Momentum states that:

In a closed system (no external forces), the total momentum before an event is equal to the total momentum after it.

Everyday Example:

Imagine two bumper cars. If one moving car hits a stationary one, the moving car slows down, and the stationary one starts moving — the total momentum is conserved and just redistributed between the two.
This principle is the reason rockets can fly in space. In the vacuum of space, when a rocket expels gas backward, the rocket moves forward — conserving total momentum

Angular Momentum

Angular momentum is the rotational version of momentum. Instead of linear motion, it deals with how objects rotate.

$$\text{<span style="font-family: helvetica;"><span style="color: \#cc0000;"> Angular Momentum (L) = moment of inertia (I) × </span><span style="color: \#cc0000;"> angular velocity (ω)</span></span>}$$

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The Law of Conservation of Angular Momentum says:
If no external torque acts on a system, its total angular momentum stays constant.

Classic Example:

Picture a figure skater spinning. With arms outstretched, they spin slowly. As they pull their arms in, they spin faster. Why? Because reducing their moment of inertia (by pulling arms in) increases their angular velocity — so total angular momentum stays the same

Why It Matters

Understanding conservation laws isn't just academic. These principles:

• Explain the behavior of systems from subatomic particles to galaxies.

• Are used in designing vehicles, spacecraft, sports gear, and amusement park rides.

• Help scientists model real-world events, from car crashes to celestial mechanics.

Conclusion

Momentum — whether linear or angular — is never lost, only shared, transformed, or redirected. These laws of conservation remind us that the universe is a grand dance of balance and symmetry, quietly maintaining order even in the most chaotic events.