Physical Science: Fluids and Dynamics Outcome C9 – Recognizing similarities and differences in natural and constructed fluid systems

Fluid systems – Section 5.5 What is a fluid system? A fluid system uses fluids to do some form of work How is this possible? To explain how this works, we need to go back to pressure and fluids

Fluid systems – Section 5.5 Fluid – is any form of matter that can flow. These include liquids and gases. They flow because they do not have a fixed shape When you apply pressure to a fluid that is at rest (not moving), that pressure builds up a force Ex: You have a tube of honey. If you squeeze the bottom of the tube, the honey will come out at the top. When a pressure is applied to a fluid in an enclosed system, the pressure is transmitted equally through the system

Fluid systems – Section 5.5 If an enclosed fluid is squeezed, then pressure is created. This pressure can be used to apply a force. Ex: if you have a pack of ketchup and you squeeze one end of it, eventually the static pressure will be high enough to exert a force great enough to break the package

Fluid systems – Section 5.5 Hydraulic systems - a device that creates a pressure that moves through a liquid Remember that liquids are incompressible. When pressure is applied onto a liquid, its volume will not change significantly. As such, a force is created and that force will be transmitted equally throughout an enclosed system. If you had liquid in a pipe (which is an enclosed system) and you applied force on one end of the pipe. The force will be transmitted to the opposite end of the pipe and it can perform certain tasks

Fluid systems – Section 5.5 Hydraulic systems is what is used to transport water into your water taps

Fluid systems – Section 5.5 Hydraulic systems require valves. Valves are used to prevent fluids from moving in the wrong direction. Imagine a turnstile

Fluid systems – Section 5.5 Hydraulic multiplication – Uses liquids in an enclosed system to transmit a force onto a surface with a large surface area. This results in the force being multiplied.

Summary: Hydraulic systems work because: It is an enclosed system. A fluid will move from Point A to Point B without being lost Liquids are incompressible substances. A pressure applied at point A will be transmitted as a force at point B. This force can be used to perform certain tasks

Pneumatic system Pneumatic system – is an enclosed system which uses gases instead of liquids When pressure is applied, the gas in the system is compressed and the volume is reduced. The particles in the gas have been squished closer together and a pressure builds up. When the pressure is released, the particles suddenly move apart from one another creating a strong, steady force

Problems in hydraulic and pneumatic systems Hydraulic systems become less effective if: Pipes are not well connected Fluid particles lose energy due to friction – bumping into other particles or the pipelines

Problems in hydraulic and pneumatic systems Pneumatic systems are less effective if: 1. The path that the gas travels is being blocked

Natural fluid systems Our body uses a hydraulic system to transport blood throughout our entire body

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