Machines can be any shape and size, but they all have one thing in common: they help people do work. When we think of machines, we usually think of big ones with many parts. These machines do big jobs, such as digging holes, washing clothes, or mowing lawns.
But some machines are small. You cut things out with a small machine – a pair of scissors. You sew with a small machine – a needle. And you tighten a screw with a small machine – a screwdriver. These small machines help you do work, too.
It’s built to last you a lifetime – quite literally. But though the human body is the most amazing tool at your disposal, it often needs a helping hand. Tools made from metal, wood, and plastic work like extensions of your body, making you feel stronger and helping you work faster and more efficiently. In science, tools like this are called simple machines. And although you might think there’s a big difference between a tiny little wrench and a huge great earthmover, exactly the same physics is at work in both.
To do anything at all—to lift a box, to push a car, to get out of bed, to jump in the air, to brush your teeth—you need to use a pushing or pulling action called a force. If you go around telling people you’re strong, what you really mean is that your body can apply a lot of force. You may have watched incredibly strong people on TV pulling trucks or trains with their bare hands, but there’s a limit to what even the most muscle-bound human body can do. Simple machines let us go beyond that limit. Simple machines can make us all strong!
Picture Credit : Google