Forces are pretty clever – they hold things together and push them apart and make things move or stop. You are held onto the earth by the force of gravity.
Gravity is a force that gets stronger for things with more mass and the closer the objects are together.
Power of the force
There are 3 other forces that we know about in nature – Electromagnetic, Strong and Weak.
Each of these forces is stronger than gravity for our small quarks. When you go to the subatomic world, you can see the quarks being affected by the forces, because there are other particles that carry the force from particle to particle.
You can’t see forces, only the effects of a force. Friction occurs when two surfaces touch each other and can slow things down when the surfaces are rough – but that can be useful (like on the soles of your trainers).
Air resistance slows things down too, that’s why many planes and cars are streamlined. On Earth, things usually stop due to air resistance and friction – that’s why car engines need to keep putting energy in to overcome this.
Forces can either be a PUSH or a PULL.
It sounds weird to have all these forces when you can’t see them, but you can certainly feel them!
If you have a bike you know riding a bike uphill is more difficult than freewheeling downhill and that’s because you’re pushing against forces on the way up but they’re right behind you on the way down!
- If you throw a tennis ball in space – where is no resistance to motion – it would just keeps on moving in a straight line with the same speed FOREVER!