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🛑Inertia vs Momentum🎳

Inertia and momentum both relate to mass and motion, but they describe different things — one resists change, the other quantifies movement.

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🛑Inertia
  • The tendency of an object to resist changes in motion
  • Depends only on mass, not on velocity
  • A property, not a quantity with units
  • Greater mass means greater inertia
  • Explains why a heavy object is hard to start or stop
🎳Momentum
  • A measure of the motion an object carries
  • Depends on both mass and velocity
  • A vector quantity measured in kilogram-meters per second
  • Zero when an object is at rest
  • Conserved in collisions within a closed system

Verdict

Inertia is the resistance an object has to changing its motion; momentum is how much motion it actually has. A parked truck has high inertia but zero momentum until it starts moving.

Frequently asked

Does a resting object have momentum?+

No. Momentum depends on velocity, so a stationary object has zero momentum despite having inertia.

What is conservation of momentum?+

In a closed system the total momentum stays constant, even through collisions.

Does inertia depend on speed?+

No. Inertia depends only on mass; momentum is the quantity that also depends on velocity.

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