Table of Contents:

-What is a Force?

-Combining Forces

-Friction

-Gravity

-(Aristotle, Galileo, and Newton)

-Newton's First Law of Motion

-Newton's Second Law of Motion

-Weight and Mass

-Newton's Third Law 

-Momentum

-Conservation of Momentum

What is a Force?

A force is a push or a pull.  These forces can cause objects to move, slow down, stop, or change direction. 

If I push my friend on the swing, they go forward.  When I push them, that's a force.  Forces play a role in our lives, every day.  

Combining Forces

When forces go in the same direction, they combine with each other and make a bigger force.  When they push in different directions, they cancel each other out or even out.  Tug of War is a great example of forces canceling each other out: both sides are pulling in the opposite direction.

Friction

Friction is the force that happens when two solid surfaces try to move across/atop of each either by sliding or rolling.  When you go sliding, that's friction.  It creates friction because the sled is sliding across the snow.  

Gravity

Gravity is another type of force.  Gravity acts upon every force that had matter or physical weight.  It pulls objects with matter towards the center of the Earth.  For example, when an apple falls from a tree, that's gravity.  

Aristotle

Aristotle set back knowledge on gravity by about 2000 years because of his pretty ridiculous claims.  He believed that every object had its place made up of one of the four elements and then they would fall back towards their natural place.  

After dropping weights off the Tower of Pisa, Galileo said that even with different masses, gravity makes all objects fall at the same acceleration.  He undid a lot of the work Aristotle did. 

Galileo

Newton

Newton is the one who made up the three Laws of Motion.  We use his laws for science today.