Newton’s relationship between force and motion. I
Newton’s First Law of Motion
Sir Isaac Newton was in my mind one of the greatest people who ever
lived. He was born in 1642 and died in 1727. He formulated three laws of
motion that help explain some very important principles of physics. Some of
Newton’s laws could only be proved under certain conditions; actual observations
and experiments made sure that they are true. Newton’s laws tell us how objects
move by describing the relationship between force and motion. I am going to try
to explain his first law in more simple terms.
Newton’s first law of motion states: A body continues in its state of
rest or uniform motion unless an unbalanced force acts on it. When a body is at
rest or in uniform motion this is called inertia. Let’s say that someone parks
a car on a flat road and forgets to put the vehicle into park. The car should
stay in that spot. This state of being is called inertia. All of a sudden the
wind picks up or some kid crashes into the car with a bike. Both the wind and
the kid’s bike crashing into the bike are unbalanced forces. The car should
start to move. The car might accelerate to two miles per hour. Now we would
all assume that the car would come to a stop sometime. We assume this because
it is true. It is true because there is friction between the tires and the road.
The car now has inertia in uniform motion. Since there is friction, the car
cannot keep moving forever because friction is an unbalanced force acting upon
What if there was not any friction? The car would keep going forever.
That is if there was not any wind or a hill or any unbalanced force acting upon
the car. This is rather weird just to think about. Because this usually would
not happen in our customary world today. You just would not see a car go on
An easy experiment to demonstrate this law is to take a glass jar and
put an index or a heavier than paper card over the top of the glass jar. Next,
place a coin on the index card. Be sure that the index card is strong enough to
support the penny without bending itself. Now place your finger about three
centimeters away from the card and flick the card out from underneath the coin.
The coin should fall into the glass jar. The inertia of the coin keeps it in
place even when the card is moving underneath it.