A pulley, also called a block and tackle, is a device that can change the direction of a force (ie, pulling downwards to raise something up), or can make it much easier to move something. You can use a pulley to move something very heavy by pulling a rope or chain through the pulley much further than you would without the pulley, but the load feels much lighter while you do it. Pulleys are used frequently in the rigging of ships.
A pump is a device used to move around fluids like water from place to place. Pumps are commonly used to get water out from below the ground. They can be hand driven, like the pump in the picture, wind driven, or driven by a motor.
A stereo, or radio is a device for playing recorded music from tapes, CDs, or listening to music that is broadcasted through the air on radio waves.
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A remote control is a device that makes other devices work without having to get up and press the buttons on them. You can change the channel on your television with a remote control.
Remote controls work by sending a signal in a beam of invisible light to the device they control. The device has a sensor on it so it can 'see' that light. This is why remote controls work best when there is nothing in between the remote control and the thing you are trying to control.
A robot is a mechanical device that appears to be able to move around and do things by itself. Robots are usually programmed by a computer so this is not strictly true. Robots are mainly used as toys, in factories, and to go places that people cannot go, like deep underwater or on other planets.
