Newton's First Law

 

If you are playing hockey and the puck is sitting on the ice, it will stay there until you hit it or another force acts on it. Why? The answer is inertia. Inertia is the tendency of an object to resist change in its motion. This means the object does not want to move. Newton’s first law is based on inertia. This is why it is sometimes called the law of inertia. It states that an object at rest will remain at rest. Also, an object moving at constant speed will keep moving at constant speed, unless acted upon by an unbalanced force.

When you hit the puck it moves across the ice. Inertia would cause it to keep moving at the same speed until it hit the boards, but the friction between the rubber puck and the uneven ice causes it to slow down. Friction is the unbalanced force that stops the puck from continuing at the same speed.

You now have your friend pushing the car with you, not against you, and you’re a quarter of the way there. After you got the car moving, you noticed it was easier to keep it moving than it was to originally start it moving. This is because it has inertia. When it wasn’t moving, its inertia made the car resist rolling. Once it was moving, the inertia made it resist slowing down.

Mass

Have you ever noticed how it is harder to move something heavy versus something light? Like if you have a balloon filled with water, and a balloon filled with air, the one that is filled with water is harder to move. This is because it has more mass. Mass is the amount of matter in an object. Mass makes it harder to move the water balloon because the more mass an object has the more inertia it has.

Now that you know this, you are happy you weren’t driving a semi truck in the car running out of gas example. You remember how the car’s inertia made it hard to push it. If the amount of inertia an object has depends on the mass of the object, the truck would have a lot of inertia because of its great mass. It would be much harder to get the semi-truck rolling than it was to get the car rolling.

 

Force Newton's First Law Newton's Second Law Friction Gravity Newton's Third Law Momentum

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Space in the Spotlight
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