Newton’s laws

• Newton's First Law

  every object will remain at rest or in uniform motion in a straight line unless compelled to change its state by the action of an external force
• example of Newton's First Law

  - a ball rolling down a hill will continue to roll unless friction or another force stops it

  - a person driving without a seat belt and he bumps into a wall, he will fly over the wall since there is nothing to stop this force (such as a seat belt)
• inertia


  the force that causes something moving to tend to continue moving, and that causes something not moving to tend to continue not to move
• what is inertial mass

  the extent to which an object resists changes in its velocity
• acceleration is ... to the resultant force

  proportional
• example of Newton's Second Law

  - a heavy person may kick the ball higher than a light person because the heavy person has more mass

  - if you use the same force to push a truck and push a car, the car will have more acceleration than the truck, because the car has less mass
• interaction pairs are...

  equal and opposite
• Newton's Third Law


  when two object interact, the forces they exert on each other are equal in size, opposite in direction
• example of Newton's Third Law

  - if you push on a wall, it will push back on you as hard as you are pushing on it

  - a ball is dropped and bounces after hitting the ground