Many different types of forces act upon us at all times, and helping children understand the basics of these forces is vital to their understanding of the world. Scientific forces include magnetism, gravity, friction and momentum. Learning about how these different forces affect the world around them is a great way to get children interested in the basic principles of physics.
Kinetic Energy and Momentum
At the most basic level, forces are things that exert a push or pull on an object. Kinetic energy is a basic movement force. When an object is moving, it has transferred a force into kinetic energy, which propels it forward. Forces can come from many different places, but the most basic force is one that can visually be applied. Pushing a toy car is a good way to show how force is converted into kinetic energy. Momentum is the accumulated force acting upon the object that will keep it travelling in the same direction. This is based on its weight and velocity.
Friction is very closely related to the basic kinetic forces, in that it is caused by a moving object rubbing against another object. Friction can be explained using shoes. The grip on shoes is designed to create friction and thereby stop us from skidding around. Friction converts the energy acting upon the object to heat, which you can demonstrate by rubbing your hands together, and thereby reduces the kinetic energy. Rough surfaces are more susceptible to friction than smooth ones.
Gravity is one of the simplest forces, and it can be illustrated through the classic story of Isaac Newton and his apple. The story goes that Newton was pondering one day under an apple tree, when one fell down and struck him on the head. This set him thinking about the fact that there is some force acting on objects to pull them downwards. Gravity is a key force in the universe, and it is that force which brought our planet into existence. Everything in the universe has a gravitational pull, which drags other objects towards its centre, and because we are living on a huge object, we are subject to its gravitational pull. The moon is also subject to the earth's gravitational pull, and the earth is held in orbit by the sun's gravitational pull.
Magnetism is another basic force that operates throughout the universe. Find a couple of bar magnets to illustrate this to children. Magnets have "north" and "south" ends, and the magnetic energy flows from the north to the south. Magnetic fields are not fully understood, but the basic principle is that opposite poles attract, and matching poles repel. Demonstrate this using the magnets. You can get the children to try to push two repelling ends of the magnet together so that they can feel the force of magnetism at work. Explain that the earth also has a magnetic field, and that is why we can use compasses.