This picture shows how an object in motion, the ball, wants to remain and motion by rolling back up the other side.
Newton’s first law of motion states that an object at rest tends to
stay at rest and an object in motion tends to stay in motion with the
same speed and in the same direction unless acted on by an outside
force. This is also called inertia. Inertia is also the tendency of a body to resist acceleration or more simply put, to keep on doing what it was doing. We know however that this isn’t true. This is because of forces
such as friction and gravity that slow things down to a stop. If in
Peck’s perfect world this law would be easy to see because no gravity
or friction would act on the body. Newton’s first law is also called
inertia. The greater mass and object has the greater its inertia. This
can be stated, “Mass and inertia are directly proportional.”
Newton's first law of motion applies to both objects in motion and objects at rest. Objects in motion have inertia because they want to remain in motion. For example a roller coaster has inertia. When it starts a drop it wants to continue moving in the same direction at a constant speed. It doesn't however because the tracks act as an outside force and change the roller coaster car's direction.
Newton's first law applies to object at rest as well. An object at rest has inertia because it wants to stay at rest. The more mass the object has the greater the tendency that it will remain at rest when another force acts on it. In the picture the car is in a state of rest, and until another force great enough to move it acts upon it, it will remain at rest.
