Physics is a very big subject. It studies lots of different things. It uses math to understand the world.
Physics studies forces. Forces are all around us. Without forces, we would not be able to drive a car or fly airplanes.
Life would be different without forces. But just what is a force? Force means pushing or pulling. Forces make objects move. Forces change the motion of objects.
We cannot see forces. But we can feel forces. We can feel them and we can see their effects.
Do you know what motion is? Motion means moving or movement. The world is full of motion.
Acceleration is a type of motion. It is a change in speed. If you push on gas in the car, it goes faster. You accelerate.
Gravity is a force. Gravity is a pulling force. Gravity pulls us down to the Earth. Without gravity, we would not be able to stay on the ground. We would float in the air! Without gravity, nothing would stay still. Everything would float around because nothing would pull it down. Gravity is an important force.
Friction is a force. Friction is a pushing force. Friction pushes against an object. Friction happens when two objects are touching each other. Friction helps objects move and stop.
Imagine rolling a pencil on a table. The pencil would not roll forever. It would slow down. Then it would stop. It slows down because of friction.
Magnetism is a force. Magnetism can be a pulling force. If a positive magnet meets a negative magnet, the two sides attract. Magnetism pulls them together.
Magnetism can also be a pushing force. If a positive magnet meets another positive magnet, the two sides repel. If a negative magnet meets another negative magnet, the two sides repel. Magnetism pushes them apart.
Physics studies electricity. Because of it, we can build electric circuits. A circuit connects a power source to something that uses the power. They are connected by wires. You can use a lever to stop the power. You can use a lever to start the power. The lights in our buildings use circuits. We use them every day.
Physics also teaches us how to convert energy. To convert is to change. We can change sunlight to electricity. We can change wind to electricity.
Physics helps us discover more about the Earth. It helps us invent new things. It can help us save the Earth.