Water can generate a considerable force when under pressure. You will know this if you have ever tried to prevent water flowing from a tap with your finger. With the use of a very simple device, the flow of water can be stopped with no effort at all. The device for the control of water flow is the tap or faucet.
It consists of a screw, which when assisted by the wheel and axle, can drive a washer downwards onto the water flow with great power. After it has been tightened, friction is created which acts on the screw thread. This action stops the screw from working loose. This screw thread is usually at a steep pitch in order to minimize the turning force needed to operate the tap.
