 How many forces can you name? Gosh, that's quite a few. In this video, we're going to look at different types of force, including contact and non-contact forces. So what exactly is a force? A force is a push or pull. Whenever you push or pull something, you're exerting a force onto it. The force that you exert can cause three things. One, you can change the shape of an object. Two, you can change the speed of an object. Or three, a force can change the direction in which something is traveling. Forces can be sorted into two groups, contact and non-contact forces. So what's the difference? A non-contact force acts against objects that are physically separated, whereas contact forces need to touch. Pause the video for a moment and think about the list of contact forces. Can you think of examples of each of these? Friction exists between two things that move over each other. Sometimes friction is useful, sometimes it's not. Friction stops you slipping off your chair. It stops you falling over when you walk. We rely on friction to slow us down when we're driving a car or riding our bikes, but friction also makes things hard to push and gives us rope burn. Tension is exerted through a rope when we pull something. Normal contact force supports an object that is resting on a surface, for example between your books and your desk. Air resistance acts on a moving object through the air. The air particles slide over the moving object, slowing it down. Pushing that box across the room has friction, normal and applied force all at once. And then spring force. It pulls the spring back into its natural resting length, whether that means squashing the spring back up or extending the spring back out. Non-contact forces act on an object whilst physically separated. Gravity is the force that attracts a body towards the centre of the earth, or towards any other physical body having mass. Having mass just means it's made of matter or stuff. Electromagnetic forces are forces that act between charged objects. For example, when you charge a balloon by rubbing it against your head and your hair is attracted to the balloon, or the forces between a magnet and a magnetic object. Nuclear forces are the strongest forces in nature. They hold the protons and neutrons together in a nucleus. In fact, because nuclear forces are so strong, is the reason why nuclear reactors produced about a million times more energy per kilogram fuel compared to oil or coal. So to summarise, forces control the way objects interact. There are lots of forces which can be grouped into contact and non-contact force. If you liked the video, give it a thumbs up. And don't forget to subscribe, comment below if you have any questions. Why not check out our Fuse School app as well? Until next time.