Take a look around you. How many machines are you aware of? Maybe you can hear a dishwasher in the kitchen. Or a vacuum cleaner being run over a carpet. Can you look out a window and see cars and buses?
These are all machines—tools that help us use energy more efficiently. They let us do more work with less labor.
The earliest machines were simple but very important. In fact, people still use them today. Nail clippers, scissors, and bottle openers all are based on a simple tool called a lever.
In the last century or so, machines have become complex. Motors that lift elevators and run blenders don’t use just gears and levers. These modern machines use electricity.
