1. Doorknob: The doorknob is a simple example of a wheel and axle system. When you turn the knob, the axle (the spindle of the doorknob) rotates and causes the door to open or close.
2. Bicycle: The wheels of a bicycle are attached to the axles of the bike's frame. When you pedal, you rotate the pedals, which are connected to the axles, and this causes the wheels to turn and propel the bike forward.
3. Car: The wheels of a car are attached to the axles of the car's suspension system. When the engine powers the wheels, the axles rotate and cause the wheels to turn, propelling the car forward.
4. Pulley: A pulley is a simple machine that consists of a wheel and a rope. When you pull on the rope, the wheel rotates and lifts the object attached to the rope. Pulleys are used in various applications, such as lifting heavy objects, changing the direction of a force, or creating a mechanical advantage.
5. Windmill: A windmill is a device that converts the kinetic energy of the wind into mechanical energy. The blades of the windmill are attached to a rotating shaft (the axle), and the wind causes the blades to rotate, which in turn rotates the shaft. The rotational energy of the shaft can be used to generate electricity, pump water, or grind grain.
6. Crank: A crank is a mechanism that converts reciprocating motion into rotary motion, or vice versa. A simple example of a crank is the hand crank of a manual food processor. When you turn the crank, the reciprocating motion of your hand is converted into rotary motion, which drives the blades of the food processor.
