Newton's First Law is:
The term that describes Newton's First Law of Motion is Inertia. Basically, an object at rest will stay at rest until another force acts on the object. For example, if you leave your science notebook on the kitchen table over night when you wake up the next morning your notebook will still be there. Even if you come to school, unless an outside force is applied to the book, your book will still be in the same place. (but you know that you should always bring your notebook back to school after you have completed your hours of homework!!!!)
Conversly, Newton;s First Law of Mtotion also states that an object in motion stays in motion. This means if you throw a baseball it will cintinue moving until an outside force acts on it. We all know that the ball will eventually fall to the ground due to the effects of gravity (outside force) and then stop due to friction between the ball and the ground. (another outside force).
In outer space it is much easier to see the effects of Newton's First Law of Motion. Objects will continue to move in the same mannor until they are stopped by an outside force.
The forces on these objects must remain balanced for an object to feel the effects of Newton;s First Law of Motion. When forces are balanced we say the object is in equilibrium. When the forces on an object are balanced the net force acting on these objects is zero. Net Force is the total force acting an object.
One of the most common places people feel the First Law is in a fast moving vehicle,
such as a car or a bus, that comes to a stop. An outside force stops the vehicle,
but the passengers, who have been moving at a high speed, are not stopped and continue
to move at the same speed. Below is an example of this:
The crash dummy is not wearing a seat belt and is moving along with the car. Both the car and the dummy are moving at, say, 60 mph.
When the car hits the cement road divider it is stopped (an outside force stops it from moving). The crash dummy, however, is not so lucky. Since he is not wearing a seat belt, and is not connected to the car, he will continue to move at 60 mph. This means he will go flying out through the front windshield (don't try this at home).
The dummy will fly through the air until he hits the ground. This is because the earth's gravity stopped him from moving any further (his trajectory is a combination of the downward force of gravity, and the horizontal force of the moving car). If this collision had happened in zero-g, in a vacuum, the dummy theoretically would keep on hurtling away from the car at 60 mph.
