Newton’s First Law

• Newton’s First Law:

  • Newton's first law of motion states:Objects will remain at rest, or move with a constant velocity unless acted on by a resultant force
  • This means if the resultant force acting on an object is zero:
  • The object will remain stationary if it was stationary before
  • The object will continue to move at the same velocity if it was moving
• When the resultant force is not zero:

  • The speed of the object can change
  • The direction of the object can change
• Applying Newton's First Law:

  • Newton's first law is used to explain why things move with a constant (or uniform) velocity
  • If the forces acting on an object are balanced, then the resultant force is zero
  • The velocity (i.e. speed and direction) can only change if a resultant force acts on the object
• • A few examples with uniform velocity are shown below:

  
• Constant velocity can only be achieved when the forces on an object are balanced - in other words, when the resultant force is zero.