Learn About Motion, Force, and Newton's Three Laws for Kids

Motion refers to movement. You might be surprised to hear that this is a really important idea in the science of Physics. Why is it so important? Simply because everything in the universe moves. You don’t feel it but you are on a planet that is moving. It is spinning around. This is called rotation.

The Earth is also moving around the sun. This is called orbiting. The whole Solar System is moving within our galaxy called the Milky Way. A galaxy is a system that contains billions of stars, gas and dust. They are all held together by a force called gravity. Everything moves all the time. So, you can see why motion is so important to scientists. Mechanics is a branch of physics that deals with the study of motion.

Isaac Newton was a famous scientist and mathematician. When he was a child he liked to build things. He built a windmill to grind wheat and a sundial to tell time.

When he grew up, he spent a lot of time learning and doing science experiments. One day, he saw an apple fall to the ground. He thought a lot about this. He figured out that a force called gravity caused the apple to fall.

Isaac Newton came up with Three Laws of Motion. These laws explain how forces act on an object. And how the object moves as a result. In the science of Physics, a force causes an object to move. Do you ever kick a ball? A ball is an object. When you kick it, you apply a force. Your kick makes a ball move. So, a force is something that can make things move. Newton also realized that gravity keeps planets orbiting around the sun.

A force can also make a moving object change direction. Imagine that you and a friend are kicking a ball to each other. When the ball comes toward you, you kick it back. You changed the direction of a moving ball.

Newton’s first law (the law of inertia) - a body at rest or moving at a constant speed in a straight line will remain at rest or keep moving in a straight line at that constant speed unless acted on by a force. Friction is one force that can act on moving bodies. Friction is caused one object rubbing against another. A ball rolling along the ground will come to a stop because friction from grass or pavement will resist its motion.

Newton’s second law - the more force applied to an object, the faster it will move. A ball that receives a hard kick will move faster than a ball that receives a gentle kick.

Newton’s third law - when you push an object, it pushes back. If you place a plate on a table, it applies a downward force equal to its weight. The table applies an equal and opposite force to the plate.