What is physics? You already know some

Why does a ball come back down when you throw it up? Why does a bulb light up when you flick a switch? Why can you hear a drum from across the room?

These questions all have one thing in common. They are about how the world works. And answering them is what physics is all about.

Physics is everywhere

Physics is the science that tries to explain how things move, how they push on each other, and how energy makes things happen. It is not only found in a laboratory. It is in everything you do:

• When you ride a bike, you use motion and forces.
• When an apple drops from a tree, that is gravity.
• When you plug in a torch and it glows, that is electricity.
• When you see a rainbow, that is light.
• When a speaker booms, that is sound.
• When you warm your hands by a fire, that is heat.

You already know some physics

You have been doing physics since you were a baby. You know that:

• a ball rolls downhill, not uphill
• a heavy box is harder to push than a light one
• ice is slippery and sandpaper is not
• a bigger push sends a ball farther

Nobody had to teach you that. You worked it out by playing. Physics just takes these things you already feel and asks: exactly how much? And why?

What do physicists actually do?

Physicists do five things, over and over:

1. Notice something interesting. "The ball goes farther when I throw it harder."
2. Ask a question. "How much farther?"
3. Test it with an experiment. Throw the ball at different speeds and see.
4. Measure the results with numbers. Write down each distance.
5. Explain what they found, so it works every time. "Double the speed and the ball goes about four times as far."

That is exactly what you do in Launch Lab. You try an angle and a speed, see what happens, and change one thing at a time.

The big topics

Physics is a big subject, so it has chapters. Here are the main ones:

In this series we start with the basics: how to measure things, then speed, forces, gravity, friction, energy and the three laws that explain motion.

How is physics different from other sciences?

• Biology studies living things.
• Chemistry studies what stuff is made of and how it changes into other stuff.
• Physics studies the rules that everything follows, including living things and chemicals. It is the base that the other sciences stand on.

How to learn physics

You do not need to be good at maths to start. You need three habits:

• Play first. Try things out.
• Predict. Before you test, guess what will happen. It makes the surprise more fun.
• Check. Was your guess right? If not, that is how you learn.