How Systems Use Inputs & Outputs

Instructor: David Wood

David has taught Honors Physics, AP Physics, IB Physics and general science courses. He has a Masters in Education, and a Bachelors in Physics.

Systems are all around us. But what are they and how do they work? Learn about inputs and outputs, then see how this lesson's input affected your mental systems by taking a quiz.

What Is a System?

A system sounds like some serious thing you might find in an office somewhere, but systems are all around us, even if you don't know it. Your school has a system for how people move between classrooms, when you learn certain subjects, and when lunch happens. A computer is a system that takes inputs and turns them into outputs. A simple light bulb is a system because it takes electrical energy in and gives light energy out. Your body contains many systems, including the circulatory system that passes blood between your heart, lungs, and other parts of the body. So what exactly is a system?

A system is a series of parts that come together to form a more complex whole to achieve a particular goal. Anything that is made up of multiple parts (or steps) and does a particular task or allows something to happen in a particular way is a system. Systems include the steps we take in doing a particular job, technology we use in our daily lives, organ systems within the human body, and societal systems like the legal system that works to keep us safe.

Diagrams can be used to represent systems
Diagrams can be used to represent systems

The one major characteristic of systems is that they have inputs and outputs. In this lesson were going to talk about that characteristic in more detail.

What Are Inputs?

An input is whatever you put into a system. For example, the body's circulatory system requires energy from food and oxygen from breathing in order to work. Those are the inputs. A computer system requires electricity and inputs from your keyboard and mouse. When you talk on the phone, you're inputting sound (your voice) into the telephone system. Inputs are whatever goes into a system.

Once something has been inputted into a system, that's when the system kicks into action. It completes whatever process (or function) the system was designed to do. For example, if you have a calculator and you input 2+3 and press the equals key, the calculator will get to work and figure out the answer to 2+3.

Systems have inputs and outputs
Systems have inputs and outputs

What Are Outputs?

Once the system has completed its process, it outputs the result. An output is whatever comes out of the system. Your body produces outputs like the air you breathe out and waste products that go into the toilet. Computer systems produce outputs like what you see on the screen. A corporation might have lots of outputs, but the final output is profits that go to shareholders. And the calculator that you typed 2+3 into will give the output of 5.

How Are Systems Useful?

In science, we try to explain the systems in the world. We look at the solar system, for example. We see the way the planets orbit the sun, and we've discovered ways to explain that using the laws of gravity. Once you know how the system works, you can use that knowledge to make predictions. For example, if we decide to do a human mission to Mars, we will look at the solar system and figure out when Mars and Earth will be closest together.

Systems exist in the natural world too, and focusing on them helps us break the world down into pieces
Systems exist in the natural world too, and focusing on them helps us break the world down into pieces

Thinking about systems is also useful for making people's lives better. If you find that you keep forgetting to bring your notebook to school, you need to look at the systems you use and fix them. What are the inputs and outputs? The output is that you forget your notebook. But what inputs lead to that problem?

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