First Law

• what is Newton's first law?

  an object has a constant velocity unless acted on by a resultant force
• if a resultant force acts on an object...

  it will accelerate (acceleration is change in velocity)

  so velocity will change

  either direction/speed/both will change
• if no resultant force acts on the object...

  an the object is stationary - will remain stationary

  and the object is moving - it will continue to move at the same velocity
• what is the tendency for objects to continue in uniform velocity

  inertia