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What is Inertia?

In the 17th century, scientist Sir Isaac Newton discovered the physics law that explains why objects do and do not move in certain ways.


The law of inertia states:

  • Objects at rest tend to stay at rest.
  • Objects in motion tend to stay in motion at the same speed and direction.
  • Objects may change their motion only if influenced by an unbalanced force.

Inertia applies not only to your vehicle, but to everything inside it. Because of inertia, your car will continue to move down the road until some other force (e.g., the brakes, road conditions, an obstruction, another vehicle) slows or stops it.

Imagine your car is traveling at 60 mph before you stop suddenly. Once the car has stopped, you and your passengers will continue moving at 60 mph because of inertia.

If you and your passengers are wearing seatbelts, they will be the force that stops you.

If you are not, the dashboard or the road ahead could become the force that stops you – which could be lethal or even fatal.

Never keep loose items in your car's cabin. They could be thrown during a sudden stop and injure someone. It is best to store items in the trunk of your vehicle when you can.