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.