FORCE: NEWTON’S THREE LAWS OF
MOTIONSarah Benson
1st Law
Newton’s first law states that an object in motion will continue in
motion in the same direction and speed unless an unbalanced force
acts against it. This is also called the law of inertia. Inertia means that
when you’re in motion you continue in the same direction and speed.
Example 1:
One example of Inertia and the first law is a seat belt. When you are in the car and you
hit something, your body automatically continues to move forward. The seat belt
however, stops your body from going out of the window and acts as the “unbalanced
force.”
The Seatbelt
Example 2: friction
When you kick a soccer ball, the automatic reaction of the ball is to keep moving in the
same direction and speed, however because of friction and gravity which work against the ball and inertia, the ball slows
to a stop.Gravity Example:
Kick
Gravity Makes it go down
2nd law
Newton’s second law states that “Acceleration of an object by a
force proportional to the mass of the object and directly
pr0portional to force applied.
Example 1: making a snowman
Building a snowman is an example of the 2nd law because it takes a lot more force to roll the bottom and middle of the body than
the head. The reason it takes a lot more force is because the bottom two spheres have more mass, therefore you have to
exert a lot more force to move them.
Example 2: cement VS. Rubber
Another example of Newton’s second law of motion is the comparison of the force
needed to roll a cement ball down a hill to a rubber ball, or a kickball. Because the cement ball has more mass than the
kickball, it would take more force to make it go at the same acceleration as a kickball.
20 N
3rd Law
The 3rd law of motion says that for every action, there is an
equal and opposite reaction.
Example 1: Rocket
A rocket is an example of the 3rd law because as the air/gasses are
released from the rocket, the pressure forces the rocket upwards.
Reaction: the rocket gets forced upwards.
pressure builds and gasses are released
Example 2: Balloon lab
Another example is our lab with the balloon. We put a straw on a string and taped an untied
balloon to it. Before releasing the balloon, we had one person hold one end of the string and the other end was attached to the cabinet. The action was the release of air from the balloon.
The reaction was the balloon going up the string.
Websites/Resources
PowerPoint clip artDearman, jennifer. “Notes over force and Motion.” truett Wilson Middle School. 2013.