Newton's First Law

N(I) in words
If an object is at rest, it will remains at rest, and if an object is already moving at a constant velocity, it will continue to move at that constant velocity, unless acted upon by a resultant force.

Newton (I) is about the absence of a resultant force!

Newton's First Law refers to an objects Inertia.
Inertia is that property of matter that keeps resting objects at rest, and keeps moving objects moving!



  1. What is the magnitude of the resultant force that acts on a resting object?
  2. An object is moving at a constant velocity of 20ms-1. What is the size of the resultant force that acts on this object?
  3. What property of matter keeps an object moving at it's constant velocity?
    it's inertia
  4. If you are in a moving vehicle and it suddenly stops, you keep moving forward. What property of matter keeps you moving forward?
    your inertia

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