5.1 The Nature of Forces Chapter 5: FORCES

WHAT IS A FORCE? Force- push or a pull When one object pushes or pulls another object, we say that the first object exerts a force on the second object Ex: I exert a force on a pen when I write. Ex 2: I exert a force on the Gorilla when I pick him up. Ex 3: I exert a force on my meter stick when I swing it.

BALANCED FORCES Balanced Forces – all forces add up to zero and do NOT change the object’s motion Forces are in the opposite direction Ex: Tug of War The rope does not move because there is a balanced force on the rope. 5 N 5 N

UNBALANCED FORCES Unbalanced Forces – net force is NOT zero so the object will change motion UNBALANCED BALANCED 2 N 5 N 5 N

UNBALANCED FORCES + = + = BALANCED FORCES + =

INERTIA Inertia – Object’s tendency to resist change in motion Ex: A truck has a large amount of inertia… imagine trying to make it stop… it’s hard because the truck has a lot of inertia

NEWTON’S FIRST LAW An object at rest will remain at rest An object in motion will remain in motion UNTIL!!! Acted upon by an outside force.

MASS Mass – the amount of matter in an object This is not the size of an object but how much mass it has Ex: A bar of metal is going to have more mass then an equal sized bar of styrofoam

Homework Study for vocab quiz Copy the diagram on page 145 of your textbook as the output on page ___ of your notebook You must draw all of the arrows You must copy all of the text