Size and Direction

-forces have a size and direction.
-small forces can't always push or pull big objects.
-the larger the mass of an object is the harder it is to push or pull it.

Examples: Your dad pushes against a box, and your 6 year old sister pushes against the same box but opposite side.
-Your little sister pushes a 50 lb box but it doesn't move because the fire isn't string enough.