Three simalar simple machnie

 Fun fact about wheel and axle is that the wheels generally spin in a balanced circle around an axle. Wheel and axel is used to move heavy objects from a place to a another place. Unlike a nail, a screw has spiral grooves down its spike. A screw is pressed down against wood and turned with a screwdriver. The grooves cut into the wood. Screws is to hold luquid into a crate so not luquid would spill. A pulley makes moving heavy loads a lot easier. A single pulley simply changes the direction of an object. Pulley is moving a heavy object from a low place to a high place