That means that if an object is moving, it tends to keep going unless something stops it, like friction or gravity. It also means that an object that is not moving stays put unless something hits it, pushes it, or pulls it.

Let’s look at some examples to demonstrate Newton’s First Law in the real world.

What would happen if you threw a ball in the air? Of course, it would go up, and then it would quickly come back down. But why does it come back down? Because Earth’s gravity pulls it back down. According to Newton’s First Law, the ball (object) would keep going up unless the ball is acted on by an outside force (gravity).

What would happen if you threw the same ball up while in outer space? It would just keep going up. In space, there is no gravity or friction. So, if you threw a ball, it would keep going until it hit something (like an asteroid or comet) or was pulled into the orbit of a planet or star.

What would happen if you rolled a ball along the floor in your classroom? It would eventually stop because of friction (the rubbing of an object against another object or surface). So the friction is the outside force that keeps the object in motion (the ball) from staying in motion.

What would happen if you rolled the same ball in outer space? Remember that there is no gravity or friction. So, if you rolled a ball, it would keep going until it hit something or was pulled into the orbit of a planet or star.

You can feel this law when you are in a moving car.

Let’s say there is a crash dummy riding in a car that is going 45 miles per hour (mph). Both the dummy and the car are moving at 45 mph. The crash dummy unwisely decided not to wear a seat belt. When the car hits a cement wall, it stops. The crash dummy does not stop because it was not connected to the car, so it has no force to stop it.

Therefore the crash dummy will keep going 45 mph. This means that he will fly through the front window of the car. The crash dummy will eventually hit the ground because the force of gravity is pulling him down.

If this happened in space the crash dummy would keep traveling 45 mph through the air until something stopped him.

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