All of your life, forces have been acting on you even though you probably don’t notice. For example, since you probably have never been in space, where there is no gravity, you have gotten so used to gravity you don’t notice it. It’s there though, along with many other forces, such as friction and inertia. By learning more about these forces, you will be able to explain why a marble falls faster than a piece of paper and why you weigh different amounts on different planets.
We tried to make our website simple by using the same example a couple of times. You have to imagine that you are riding in a car with your friend, and your car runs out of gas. You are trying to get home, but to get there you have to understand how forces work. We’ll use this event to teach you a lot about forces and motion.
Every time you move something, use your pencil, or walk, you are using force. These forces are examples of everyday life because that is what a force is, everyday life. Every day you use force to make your life easier. Sometimes it is hard to understand how forces help you.
Newton’s first law of motion explains inertia, another force. Inertia helps explain why things stay where they are. Think about how many times you would lose your papers if inertia didn’t make it stay where you put it.
Sir Isaac Newton thought that you could find the acceleration of an object, so he wrote this law to explain how. It states that acceleration equals force divided by mass.
Friction is a force that slows things down. This force can be both useful and harmful. Friction has two affects on a capsule reentering Earth’s atmosphere. The friction between the capsule and the atmosphere cause extreme heat. This is the harmful part. After the capsule comes through the atmosphere it uses parachutes to slow it down. The parachutes use air resistance, a type of friction, to slow it down. Without fiction the capsule would not slow down.
You may want to become an astronaut so you could float around, but do you know why you would float? The reason is there is no gravity in space. Gravity is the force that pulls you towards Earth.
Newton’s third law says that for every action there is an equal and opposite reaction. Rockets are propelled upward because of a reaction force. The exhaust gases cause a reaction force that pushes the rocket into the air.
Momentum is a force that makes it hard to stop an object. If you were running, you would have momentum. Because of this, if you tried to stop really fast, you might fall because the momentum wants you to keep going forward.
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All pictures courtesy of NASA unless otherwise noted